P142-1 People have discovered the principles of solar energy whenever fuel becomes scarce and expensive but will forget them every time a new source of cheap energy is developed. (A) have discovered the principles of solar energy whenever fuel becomes scarce and expensive but will forget (B) have discovered the principles of solar energy whenever fuel has become scarce and expensive but they forget (C) discovered the principles of solar energy every time fuel becomes scarce and expensive, forgetting (D) discover the principles of solar energy every time fuel became scarce and expensive, but they forget (E) discover the principles of solar energy whenever fuel becomes scarce and expensive but forget 句子有点晦涩啊。forget是用倒装么？如果倒装的话不是应该把整个宾语提前么？ P141-18 Intended primarily to stimulate family summer travel, the new airfare, which allows both an adult and a child to fly for the price of one ticket, and also shortens the advance-purchase requirement for family travel to a minimum of seven days rather than fourteen.
(A) and also shortens the advance-purchase require- ment for family travel to a minimum of seven days rather than (B) and also lessens the advance-purchase requirement for family travel to a seven-day minimum from (C) also shortens the advance-purchase requirement for family travel to a minimum of seven days rather than that of (D) also lessens the advance-purchase requirement for family travel to a seven-day minimum from (E) also shortens the advance-purchase requirement for family travel to a minimum of seven days rather than
A为什么错呢？不是用and更对称么？还是说and also罗嗦啊？
When drive-ins were at the height of their popularity in the late 1950's, some 4,000 existed in the United States, but today there are less than one-quarter that many.
A. there are less than one-quarter that many B. there are fewer than one-quarter as many C. there are fewer than one-quarter of that amount D. the number is less than one-quarter the amount E. it is less than one-quarter of that amount 为什么选择C呢?不是说只有在修饰人的时候才用few么？
首先 but之前的句子使用完成时态是不好的
People discover the principles of solar energy whenever fuel becomes scarce and expensive ..
这句话里的时间状语从句whenever fuel becomes scarce and expensive实际上描述一个经常性习惯性的状态所以完成时态不好 应该用一般式
同样but句后面仍然应该用一般式，并且but句中的时间状语从句应该也使用一般时态
这样看只能是选择E选项
P141-18
这个题目A选项的错误其实是相对明显的
这个句子中 Intended ... travel是状语
主句主语是 the new airfare, 后面的which allows both and adult and a child to fly for the price of one ticket是一个定语，后面的shortens其实应该做句子的谓语动词
从这个角度上看，and在shortens前面 语法上要引导一个并列结构，但是在句子中却没有任何一个谓语动词能够和shorten并列
当然你也可以认为shorten 和前面的allow并列，但如果这样的话句子就缺少谓语动词 不完整了
