1. The policeman is investigating the ____ about the traffic accident.

　　A. passer-by B. passers-by C. passer-bys D. passers-bys

　　2. This is the first time I ____ her sing. And I hope it is the last.

　　A. heard B. hear C. will have heard D. have heard

　　3. Dr. Jonathan, together with his assistants, ____ operating on the patient.

　　A. are B. is C. have D. has

　　4. My brother has just arrived. But I didn’t know he ___ until yesterday.

　　A. came B. will came C. was coming D. have been coming

　　5. By the time I got downstairs, the telephone _____.

　　A. stopped ringing B. would have stopped ringing

　　C. had stopped ringing D. stopped to ring

　　答案与解析：

　　1.[B]

　　解析：复合名词的复数形式一般加在主体词上，如果没有主体词，就只在最后一个词上加复数词尾。

　　2.[D]

　　解析：“This/That/It is the first time that…”结构中，that中从句用现在完成时。

　　3.[B]

　　解析：“together with his assistants” 是插入语，真正的主语是Dr. Jonathan , 所以谓语用单数形式。

　　4.[C]

　　解析：leave/ come/ go/ arrive等瞬间性动词常用进行时表示计划好或即将发生的动作。

　　5.[C]

　　解析：“By the time I got downstairs”限定了过去时间参照点，stop为过去的某一动作之前已完成的动作。