Nowadays many parents make their children study various subjects _________ weekends.

A. with B. at C. by D. to

Over 20 countries joined to search _________ Flight MH370 in the southern Indian Ocean.

A. of B. for C. in D. from

Although advertisements enable _________ to make decisions quickly, they sometimes cause lots of trouble.

A. we B. our C. us D. ours

--Did you see Mary and her sister this morning?

-- Yes, I saw _________ girls playing in the playground.

A. either B. neither C. any D. both

This summer vocation I am going to do a lot of _________ to prepare for the senior high school.

A. job B. work C. invention D. service

For the safety, everyone _________ obey the traffic rules when he is driving or walking.

A. need B. must C. may D. could

I’d like to travel by air _________ it usually costs a lot of money.

A. so B. though C. until D. or

．It is said that a wooden bridge_________ over the river in the mountain village soon.

A. build B. will be built C. will build D. built

In recent years the environmental pollution has been _________ than before.

A. so serious B. serious C. more serious D. too serious

To live a green life, we try_________ more energy and produce less pollution.

A. to save B. save C. saves D. saved