Scientists have invented artificially intelligent computer systems ______ of answering questions posed in natural language.

B. was carrying

C. was carried

D. has been carried

 A. advise/ give    

 B. to advise/ to give

 C. advising/ giving   

 D. advising/ to give

A. how long you have studied English

B. how long had you studied English

C. how long you had study English

D. how long you had studied English

A. plainly

B. properly

C. flashily

D. soberly

A. attractive

B. effortless

C. inelegant

D. sophisticated

A. John doesn’t write home once a week any longer.

B. John enjoyed being written home every week when he was abroad.

C. John never forgot to write a weekly letter home when he was abroad.

D. When he was abroad he remembered to write home every week.

A. came out

B. went out

C. pulled out

D. broke out