Such problems( )air pollution and traffic jams are becoming more and more serious in some big cities.

A. lay

B. lain

C. lied

D. laid

A. what is needed

B. is needed

C. that is needed

D. the needed thing

A. might pass

B. might have passed

C. has passed

D. had passed

A. decided

B. made

C. resisted

D. adopted

A. some time

B. sometime

C. some times

D. sometimes

A. on

B. in

C. to

D. from

A. able to

B. capable to

C. able of

D. capable of

A) incapableB) indispensable

C) insensible D) infinite

A) set back B) stood back

C) held up D) kept down