略，遗漏"。

　　10．Since you have committed yourself to ________ care of your friend's son, you should do your best.

　　A．take B．taking

　　C．being taken D．be taken

　　解析：选B　当commit作"答应，承诺"讲时，常用于commit oneself to doing sth.结构。

　　11．(辽宁高考)Leave your key with your neighbor ________ you lock yourself out one day.

　　A．as long as B．even though

　　C．in case D．as if

　　解析：选C　句意：把你的钥匙留给你的邻居，以防有一天你把自己锁在外面了。as long as"只要"；even though"尽管"；in case"以防"；as if"好像"。所以选C。

　　12．-Look, it's raining so heavily. I'm tired of this weather.

　　-________.

　　A．So do I B．So am I

　　C．So I do D．So I am

　　解析：选B　当表示前面所说的肯定的情况也适用于后者时，常用"So＋be动词/助动词/情态动词＋主语"结构；再根据"I'm tired of this weather"可知选B项。

　　13．Mr.Reed, with his wife and two kids, ________ the US for Christmas, but they haven't decided when to set off.

　　A．is returning to B．are returning to

　　C．has returned to D．have returned to

　　解析：选A　主语后面跟有with短语时，谓语动词的单复数形式与with短语前的主语一致，故谓语动词用单数形式，排除B、D两项；由语境"they haven't decided when to set off"可知，这里用现在进行时表示将来。

　　14．We didn't think Jim could cover the distance in a quarter of an hour. ________， he succeeded in doing it.

　　A．Otherwise B．Besides

　　C．Anyway D．However

解析：选D　句意：我们认为吉姆不可能在一刻钟内走完那段距离，但他却成功做到