People in China are proud of ______ they have achieved in the past few years.

A. what        B. which             C. that            D. how

 Gun control is a subject ______ Americans have argued for a long time.

A. of which    B. with which        C. over which      D. into which

 ______ the Internet is of great help, I don’t think it’s a good idea to spend too much time on it.

A. If          B. As                C. Because         D. While

 So sudden ______ that the workers left behind had no time to escape.

A. did the outbreak of the fire     B. the outbreak of the fire did

C. was the outbreak of the fire     D. the outbreak of the fire was

 When first 　　　 to the market, these products enjoyed great success.   

A. introducing B. introduced        C. to introduce    D. being introduced

 It remains ________ whether he will be experienced enough to take over the business.

A. seen        B. to be seen        C. seeing          D. to see

 --- Jack lost new mobile phone the other day.

--- ________? That’s his third one in just one month.

A. Had he     B. Did he            C. Does he         D. Has he

 It was not until _______ together for a couple of weeks ____ I found we had a lot in common.

A. we stayed, that                  B. did we stay, that   

C. we stayed, when                  D. did we stay, when

 --- My stomach hurts badly.

   --- You ______ have eaten so many mangoes.

A. wouldn’t                        B. couldn’t            C. shouldn’t        D. mustn’t

 –What’s that noise?

  –Oh, I forgot to tell you. The new machine ______.

A. was tested    B. will be tested          C. is being tested    D. has been tested