immediately.

　　解析：句意：医生坚持说病人处境危险，应该立刻动手术。in danger在危险中。

　　12．The difference between Tom and Mike lies in __how__ they employ their spare time.

　　解析：句意：汤姆与迈克的不同之处在于他们如何利用他们的业余时间。employ在此意为"利用"。

　　13．A sharp decrease __in__ production was seen due to the bad management.

　　解析：句意：由于糟糕的管理，生产迅速下降。

　　14．-How do you __respond__(response) to her rude behavior?

　　-Only silence.

　　解析：句意：--你是如何回应她的不礼貌行为的？--只有沉默。respond to对......做出反应，对......做出回答，符合题意。

　　15．It is certain __that__ he will hand over his business to his son when he gets old.

　　 解析：句意：当他变老时，他将把他的企业移交给他的儿子，这是确定无疑的。It is certain that...确定无疑......。