With extra evidence John Snow was able to______(宣布) with certainty that polluted water carried the virus.

In the 1950s, the Chinese government introduced ________（簡化）Chinese characters and now they are used widely in mainland China.

But for your timely help,the boy　　 his life.

A、will lose　 B、has surely lost　　 C、might have lost　　　 D、shouldn’t have lost

　　　 my hometown take on a new look, a sense of　　 suddenly appeared in my mind.

A. Having seen; joy　　　　　　　　 　　　　　　　 B. Seeing; happiness

C. While I saw; delight　　　　　　 　　　　　　 D. When I saw; pride

In aerospace devices the weight of the necessary power producing equipment is _____.

　　A. vital 　　 B. possible 　　 C. capable　　 D. reliable

They may go swimming with us ____________ they arrive here in time.
A. provided     B. because      C. unless       D. even if

When I met my friend, he asked me _____ I was getting along well with my new job.

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

Eliza remembers everything exactly as if it ______ yesterday.
A. was happening B. happens    C. has happened   D. happened

Joseph ______to evening classes since last month, but he still can’t say “What’s your name?” in Russian.

A. has been going　 B. went　　　　　 C. goes　　　　　　 D. has gone

Selecting a mobile phone for personal use is no easy task because technology _______ so rapidly.

A. is changing B. has changed C. will have changed D. will change