有3題關於英文文法(時態)不懂，有誰可以幫我講解

Question

1.When did mankind reach the moon for the first time?
(A)For thousands of years. (B)For one day. (C)On July21,1969.
(D)Before they go.
答案為啥要選C呢?

2.His sprained ankle prevented him from walking, so he______to the
nearest road.
(A)has to crawl (B)had to crawl (C)having crawled
(D)having been crawling
為何答案要選B呢?

3.We have been told the final outcome of the negotiations, but we shall
never know what _______on behind the scenes.
(A)goes (B)will go(C)went (D)will have been going
答案為何要選C呢?

Answer 1

1. When did mankind reach the moon for the first time?
(A)For thousands of years. (B)For one day. (C)On July 21, 1969.
(D)Before they go.
答案為啥要選C呢?
1. 各選項的意思為: (A) for thousands of years 有幾千年之久(B)有一天之久(C)在1969年7月21日那天.(D)在他們去之前.
2. 本題目在問:人類於何時第一次登陸月球?因此只有(C)選項吻合題意.
2. His sprained ankle prevented him from walking, so he______to the nearest road.
(A)has to crawl (B)had to crawl (C)having crawled
(D)having been crawling
為何答案要選B呢?
1. 本題是說他因為扭傷的腳踝阻礙他走路,所以他必須用爬的到最近的路上去(求助).
2. so為副詞性連接詞,連接兩個對等的子句,前面表原因的子句中,動詞用的是過去式的prevented,因此在表結果的子句中,動詞也要用過去式的had.
3. 本句是陳述發生在過去的事實,動詞用簡單過去式即可.
a. (A)為現在式,(C)和(D)選項少了動詞均不能成為正確選項.
b. 只有(B) 選項符合要求.
3. We have been told the final outcome of the negotiations, but we shall
never know what _______on behind the scenes.
(A)goes (B)will go(C)went (D)will have been going
答案為何要選C呢?
1. 本題是說我們被告知了協商的最後結果,然而我卻無從了解協商背後發生了什麼事.
2. 被告知是現在的事情,故用現在完成.
3. 協商的動作是發生在過去,因此協商背後所發生的動作也得用過去式動went.
a. (A)是現在式,(B)是未來式,(D)是未來完成進行式,都不能成為正確選項,
b. 只有(C) 選項符合要求.

Answer 2

1.When did mankind reach the moon for the first time?
(A)For thousands of years. (B)For one day. (C)On July21,1969.
(D)Before they go.
答案為啥要選C呢?
句意：人類何時首次登月?
答案當然是要選正確的日期。也就是1969年，七月21日囉。

2.His sprained ankle prevented him from walking, so he______to the
nearest road.
(A)has to crawl (B)had to crawl (C)having crawled
(D)having been crawling
為何答案要選B呢?
句意：他那扭傷的腳踝讓他無法行走，所以他必須爬到最近的道路上。
前半句的prevented是過去式，因此後半句，也必須用過去式的
had to來表達。
3.We have been told the final outcome of the negotiations, but we shall
never know what _______on behind the scenes.
(A)goes (B)will go(C)went (D)will have been going
答案為何要選C呢?
句意：我們已經被告知協商的最後結果……可是我們將永遠不會
知道，到底幕後的運作情形是如何了。
因為協商已經結束，因此用過去式went(go的過去式)來表示。

Answer 3

1.這是問人類登月的事實,當然是C.
2. 因為這是過去式(看"prevented")
3.用"went"也是表示過去式,已經發生了.