() 5. —What ______ if they ______ to the airport late?
—Sorry,I don't know.

A.will happen；go
B.happened；go
C.happens；will go
D.will happen；will go

A

本题考查的是条件状语从句的时态用法，在条件状语从句中，从句用一般现在时表示将来，主句用一般将来时。题干中，if 后面的是从句，要用一般现在时，而主句“他们如果去机场迟了会发生什么（what）”，要用一般将来时。选项A，主句一般将来时，从句一般现在时，正确。选项B，主句过去时，从句一般现在时，不符合主句一般将来时的用法。选项C，主句一般现在时，从句一般将来时，不符合从句一般现在时的规则。选项D，主句一般将来时，从句一般将来时，从句不符合一般现在时的规则。因此，A是正确的选项。

Ⅱ. 根据句意,用括号中所给词的适当形式填空
1. If you careful in the exam,you will get good grades. (be)
2. If you (press) the button,the light ______ (turn) on.
3. If David time next weekend,he will go to the zoo. (have)
4. The children will go to the zoo if it this Sunday. (not rain)
5. She shopping with her parents if it snows this afternoon. (not go)

1. are 2. press, will turn 3. has 4. doesn't rain 5. won't go

1. 此句为if引导的条件状语从句，遵循“主将从现”原则，从句主语是you，be动词用are。
2. if引导条件状语从句，“主将从现”，从句主语是you，动词用原形press；主句用一般将来时will turn。
3. 条件状语从句“主将从现”，从句主语David是第三人称单数，have用has。
4. if从句“主将从现”，否定形式借助助动词doesn't，后接动词原形rain。
5. 主句用一般将来时，否定形式在will后加not，缩写为won't，后接动词原形go。

探究点1 difficulty的用法
difficulty名词,意为“困难；难题”。have difficulties (in) doing sth表示“做某事有困难”。
We found the house without difficulty.
我们轻而易举地找到了这栋房子。
He has difficulties (in) solving the problem.
他解决这个问题有困难。
[知识拓展]
difficult形容词,意为“困难的”,其比较级是more difficult,最高级是most difficult。
Of all the subjects,maths seems to be the most difficult for me.
对我来说,数学似乎是所有学科中最难的。
情境应用
1. No matter how many we meet,we believe we can solve them. (difficult)
2. Among all the tasks,this one is . (最难的)
3. When he English,I will help him. (在……方面有困难)

1. difficulties 2. the most difficult 3. has difficulty (in) learning

1. 空格前有many修饰，需用difficult的名词复数形式difficulties。
2. “最难的”对应difficult的最高级most difficult，前面加定冠词the。
3. “在……方面有困难”用固定搭配have difficulty (in) doing sth，主语he是第三人称单数，动词have用has，“学英语”为learning English，可省略in。

探究点2 line的用法
|line|作名词,意为“行；便条；路线”|
| |I forget how the next line says. 我忘记下一行怎么说了。|
| |drop sb a line意为“给……写信”|
| |Drop me a line when you get there. 你到那儿后给我写封信。|
| |wait in line意为“排队等候”|
| |It's necessary for us to wait in line in public. 对我们来说,在公共场合排队等候是有必要的。|
| |cut in line意为“插队”|
| |It is impolite to cut in line. He should wait his turn. 插队是不礼貌的。他应该等着轮到自己。|

情境应用
1. Here is a for you on the table. (便条)
2. I often ,sharing with him my happiness. (给他写信)
3. She is to buy tickets. (排队等候)
4. When we see someone ,we may ask him to join the line politely. (插队)

1. line 2. drop him a line 3. waiting in line 4. cutting in line

1. 根据“便条”及前面的不定冠词a，可知填名词line。
2. 根据“给他写信”及often可知用一般现在时，主语I，谓语用动词原形，填drop him a line。
3. 根据“排队等候”及is可知用现在进行时，填waiting in line。
4. 根据“插队”及see sb doing sth，填cutting in line。