帮忙解释几道英语语法题.(不只是答案,)

1.What do you think _____ at his house now?
A.he may be doingB.may he be doingC.maybe he doingD.he maybe doing
选A
首先句中之句要用陈述句的语序
may be在句子中间,所以分开（自己的总结……）
2.I have no idea ____
A.how does this cooker work B. how this cooker works
C.how works this cooker D.how did this cooker work
还是句中之句,陈述句的语序（主语在疑问词之后）选B
3.There are many ____ to spend our free time.
A.waysB.placesC.friendsD.games
A,way代表的是方式,如果选B则要有介词,这里没有,所以选A
4.Each student is allowed to choose two ___ these books.
A.of B.with C.at D.for
A,表示这些书中的一些,B（表伴随状态）C（……）D（有为了的意思）皆不通
5.I kept it ___ in my heart.
A.deeply B.deep C.warmlyD.warm.
B,系动词（keep）之后根形容词（D是明显的没这种说法）
6.What time is ____ for you?
A.freeB.availableC.convenientD.busy
C,（……凭语感……）
用单词的适当形式填空.
7.I____(have) English classes every Monday.
填have
因为是每个星期一,所以是一般现在时
8.We ___ never ___ (hear) of this man before.
have……heard,因为是never和before所以是现在完成时
表示到现在为止的一个状态
（hear heard heard ）
9.They _____ (ride) on the same bus to school every morning.
ride
因为是every morning,于是用一般现在时
10.They ____ (not,get) their books yet.They're still waiting.
haven't got
因为有yet,所以是现在完成时,
主语复数,所以用have
（get got got/gotten）
11.He ____ (not,make) any mistakes since September.
hasn't made
因为有since,所以是现在完成时
（make made made）