______the explosion occurred was that the laboratory attendant had been careless.
A．That
B．What
C．Why
D．How

未分类题______finished speaking when someone rose to refute his points.A．Hardly he hadB．He hardly hasC．Had he hardlyD．Hardly had he

未分类题Which of the following statements is true according to Para. 3?A．Prevention strategies have not been used as widely as they should be.B．All the deadly injuries come from car accidents for the 15 years old.C．Children aged from 5 to 14 are more likely to be injured by car.D．A new driver has to buy a child seat to prevent children injuries.

未分类题What is the problem that Facebook is faced with?A．Lack of social support, it is hard for Facebook to become popular.B．It meets difficulties when Facebook makes ads in a social network.C．Facebook meets with intense competition from new rivals like Twitter.D．It is difficult for Facebook to make ads online just as offline.

未分类题What can be inferred from the passage?A．Twitter would like to make the word 'resonant' a popular buzzword.B．The ads that are resonated by most users are the best ones.C．Twitter's 'resonant' strategy is proved to be successful.D．Companies may run a risk if they pay for Twitter's ads.

未分类题From the first sentence of the passage, we learn that______A．acid rain has caused air pollutionB．acid rain has caused widespread environmental damageC．acid, rain has become a much studied subjectD．acid rain travels in all directions before it rains down