Children under sixteen are not permitted to participate in such kind of activities _____ bad for their mental development.

A. as is            B. as are               C. that are         D. that they are

According to China's Food Safety Law, ______________ in February 2009, the State Council established the Food Safety Committee to oversee a chain of departments.

A. as is passed   B. as it was passed

C. which is passed   D. which was passed

（2010·江苏淮安中学高三第一次阶段闯关测试）   33. Paper was invented by ancient Chinese, ______gunpowder.

A. as is          B. as was        C. as did D. as

 The Internet is a wonderful discovery, ________of great significance to people’s lives.

  A. as is I think     B. which I think it is    C. as I think    D. which I think is

_____quite common for people to believe that more and more teenagers have become addicted to on line games.?

A.As is                            B.That is     C.It is                            D.What is ?