One recent prediction is that within the next 50 years, it ______ possible to link the human brain directly with a computer．

A．is                   B．will be                   C．would be                 D．was

With so little time ______ on math, it is all too easy for children to ignore practicing mathematics, which is a kind of language．

A．spent          B．being spent            C．to spend          D．was spent

Even if there is no scientific proof yet ______ secondhand smoke causes cancer, there is no reason why nonsmokers should be forced to take this risk．

A．which          B．that         C．when           D．where

—Do you know when Phil's coming?

—He ______ 4: 00．

A．says           B．has said           C．had said         D．said

You ______ very fast if you went from New York to Boston in six hours．

A．should drive                                       B．would have driven

C．may drive                                        D．must have driven

—How did he break his head while swimming?

—______ my warnings, he dived straight into the shallow water．

A．To ignore               B．Ignored             C．Ignoring               D．Being ignored

Napoleon would have taken over the world if he ______ the Battle of Waterloo．

A．wins         B．won        C．had won        D．has won

—Can you tell me what time the flight to Detroit leaves?

—I'm sorry, but it ______．

A．has been canceled                     B．had been canceled

C．has canceled                            D．had canceled

My parents send me to a school _____ rules are just as important a part of education as the academic subjects．

A．that          B．which         C．where        D．when

Both of the two boys are enjoying their lives ______ the fact that they have very little time to do other things．

A．beside             B．despite            C．beyond           D．except