Exploring really deep caves is not a task for the Sunday afternoon rambler.

the + 名词 ^类指

• Horses are useful animals. ^主谓一致
• The horse is a useful animal.
• A horse is a useful animal.

...is not a task for sb. ^{不是某人所能胜任的}

• Studying abroad is not a task for the lazy-bones. ^{出国留学不是懒汉所能胜任的。}
• Being a good husband is not a task for the playboy. ^{做个好老公不是花花公子能胜任的。}

Such undertakings require the precise planning and foresight of military operations.

require the precise planning and foresight of ... ^{需要精确的计划和远见…}

• Speculation in stocks requires the precise planning and foresight of a professional investor.^{炒股需要一个职业投资人的精密计划和远见。}

It can take as long as eight days to rig up rope ladders and to establish supply bases before a descent can be made into a very deep cave.

take ^{v.需要...(时间、人、事物)}

• The wound will take a long time to heal.
• It takes two people to make a quarrel.
• You're an idiot! —It takes one to know one !

Anyone can be passionate, but it takes real lovers to be silly. — Rose Franken

rig up ^{to make sth. quickly out of whatever you can find 草草做成，草草搭起}

• They rigged up a shelter using a sheet and some branches.
• We managed to rig up a shelter for the night. ^{我们匆匆搭了个棚子过夜。}

make a descent = descend ^下降

• ... before pot-holers can descend into a very deep cave. ^{替换为人做主语}

Precautions of this sort are necessary, for it is impossible to foretell the exact nature of the difficulties which will confront the pot-holer.

This sort of precaution is necessary, ... ^{替换（但Precautions习惯用复数）}

precaution ^{n.预防措施（常用复数）}

• fire / safety / security / sanitary precautions ^{防火/安全/保安/卫生预防措施}

confront / face sb. ^{面对某人（摆在面前）}

• She decided to confront him about his lies. ^{她决定直面他对他的谎言。}
• He had to face his boss with the bad news. ^{他不得不面对老板说出坏消息。}

The deepest known cave in the world is the Gouffre Berger near Grenoble.

known ^{adj.已知的、已发现的；知名的，出了名的}

• little-known ^{鲜为人知的}
• unknown ^未知的
• well-known ^{众所周知的}

It extends to a depth of 3,723 feet.

extend to a depth of ... ^深达...

• The platforms extend to a depth of over 100 feet under the sea.

This immense chasm has been formed by an underground stream which has tunneled a course through a flaw in the rocks.

chasm ^{n.深渊，峡谷}

• Chasmal definition is resembling a chasm. ^{峡谷的定义是类似于一个裂口。}
• It is more of a chasm than a gap. ^{但这显然是一个鸿沟而不是什么缺口。}
• So why the growing chasm? ^{差距为什么越来越大？}
• The present gap is really more of a chasm. ^{目前的差距越来越大了。}
• The tourists luxuriated in the beauties of the chasm. ^{游客们尽情地享受这个峡谷的美景。}

tunnel ^{n.隧道，地道 v.开凿隧道，挖地道}

• The thieves tunnelled under all the security devices.  ^{小偷们在所有的那些安全装置下面都挖了地道。}
• He passed down the tunnel. ^{他穿过隧道。}
• The tunnel would be well-ventilated if tall chimneys were built above sea level.

The entrance to the cave is on a plateau in the Dauphine Alps.

plateau ^n.高原

• The Qinghai-Xizang Plateau has long been known as the roof of the world. ^{青藏高原素有世界屋脊之称。}

* The cave might never have been discovered had not the entrance been spotted by the distinguished French pot-holer, Berger.

If + S. + did / were, S. + would / should / could / might + do ^{与现在的事实相反}

• 'Young man,' she answered, 'if you ate more and talked less, we would both enjoy our dinner!'
• The tunnel would be well-ventilated if tall chimneys were built above sea level.

当 were、had ^{做助动词时}、should 放到句首即可倒装并去掉“if” ^{仅用于正式场合的演讲与作文中}

• If I were you, I would go abroad at once. →  Were I you, I would go abroad at once. 
• If you had come here a little earlier just now, you might have met her. → Had you come here a little earlier just now, you might have met her.
• If it should rain tomorrow, you could stay at home. →  Should it rain tomorrow, you could stay at home.
• If the sun were to rise in the west, I would lend you the money. →  Were the sun to rise in the west, I would lend you the money.

Since its discovery, it has become a sort of potholers' Everest.

a sort / kind of ... ^{好像是...、貌似...}

• We sometimes imagine a desert island to be a sort of paradise where the sun always shines.
• In spite of this, the Italians regarded him as a sort of hero.

Since its discovery, it has become, as it were, the pot-holer's Everest. ^替换
Since its discovery, it has become, so to speak, the pot-holer's Everest.

Though a number of descents have been made, much of it still remains to be explored.

remain to be done ^有待于..

• Several problems remain to be settled.
• It remains to be seen how many senior citizens will actually benefit from this new plan.