不要混淆祈使句与非谓语动词

有这样一道语法考题，该用动词原形？还是用非谓语动词？

_________ the road round to the right and you’ll find his house.

A. Follow                     B. Following                     C. To follow                      D. Followed

【分析】此题容易误选B或C，许多同学一看选项就想当然地认为，选现在分词表示时间或伴随，选不定式表目的。此题的关键是要注意句中的连词and，它表明整个句子是一个并列句，即 and 前后应各是一个独立的句子，而不应是一个非谓语形式的短语，所以此题的正确答案应选A，即 and 前是一个祈使句。比较以下两题：

(1) _________ the road round to the right, she found his house.

A. Follow                        B. Following                        C. To follow                        D. Followed

【分析】此题应选B，现在分词短语表时间。

(2) _________ the road round to the right, the blind man asked a boy to guide him.

A. Follow                        B. Following                        C. To follow                        D. Followed

【分析】此题应选C，不定式短语表目的。

注意以下各题均应选A，均因为句中的并列连词 and（填空句为祈使句）：

(1) _________ the milk and set a good example to the other children.

A. Drink                        B. To drink                          C. Drinking                        D. Having drinking

(2) _________ me, and don’t just stand there laughing.

A. Answer                     B. To answer                    C. Answering                        D. To be answering

(3) _________ me , and then try to copy what I do.

A. Watch                        B. Watching                     C. To watch                        D. Have watching

(4) _________ through this book and tell me what you think of it.

A. Look                          B. Looking                        C. To look                        D. Having looked

(5) _________ it with me and I’ll see what I can do.

A. Leave                         B. Leaving                        C. If you leave                    D. When left

注：有时可能不用连词，而用破折号（答案均选B，填空句为祈使句）。如：

(1) _________ down the radio — the baby’s asleep in the next room.

A. Turning                        B. Turn                          C. Turned                        D. To turn        

(2) _________ some of this juice — perhaps you will like it.

A. Trying                          B. Try                           C. To try                        D. Having tried

以下各题也应选A，是因为句中的从属连词 when, before, until 等（填空句为祈使句）：

(1) _________ left when you get to the end of the street.

A. Keep                            B. Keeping                     C. To keep                        D. Kept

(2) _________ you hand over your mouth when you cough.

A. Put                              B. Putting                      C. To put                          D. To be putting

(3) _________ him enough time to get home before you telephone.

A. Give                            B. To give                     C. Giving                          D. Given

(4)_________ until the lights have turned to green.

A. Wait                            B. To wait                     C. Waiting                        D. Having waited

(5) _________ the pieces of cloth with a loose stitch before finally sewing them together.

A. Join                             B. To join                      C. Joining                        D. Joined

以下各题也应选A，即填空句为祈使句：

(1) Don’t give me a long account, just _________ the plain facts.

A. tell                              B. telling                        C. to tell                           D. to be telling

(2) First _________ the rice by washing it, then _________ it in boiling water.

A. prepare, cook               B. preparing, cooking     C. preparing, cook             D. prepare, cooking

(3) Don’t sit there watching — _________ and help me!

A. come                           B. coming                      C. to come                        D. to be coming

(4) Don’t waste your money on silly things — _________ it.

A. save                            B. to save                        C. saving                        D. having saved

(5) To test eggs, _________ them in a bowl of water: if they float they’re bad, if they sink they’re good.

A. put                             B. putting                        C. to put                         D. to be putting

但是，以下各题情形有所不同，所填部分为目的状语(用不定式，即答案均为B)：

(1) _________ late in the morning, Bob turned off the alarm.

A. Sleep                           B. To sleep                     C. Sleeping                      D. Having slept

(2) _________ the early bus, Mr Smith got up at six.

A. Catch                          B. To catch                     C. Catching                     D. Having caught