28.—Mr.White has a toothache.

—It’s been hurting him for quite a while，______？（  ）

A.hasn’t it

B.doesn’t it

C.wasn’t it

D.isn’t it

28.A【解析】句意：—怀特先生牙疼。—他已经牙疼好一阵子了，对吗？由句意得知，牙疼的状态一直在持续，需用现在完成时，故反意疑问的形式为助动词+not+it主语。故A正确。

29.He was delighted at______.（  ）

A.how the airline had been efficient

B.how efficient the airline had been

C.how efficient had been the airline

D.how had the airline been efficient

29.B【解析】句意：他对飞机航线的高效率感到很高兴。delighted at 后面接宾语从句，用陈述语序。故选B。

30.A university is an educated institution which awards degrees and ______ research.（  ）

A.carries forward

B.carries through

C.carries off

D.carries out

30.D【解析】句意：大学是一个授予学位和开展科学研究的教育机构。carry forward“发扬，推进”；carry through“贯彻，完成”；carry off“获得，夺去”；carry out“执行，贯彻，开展”。需注意carry through常用作carry sb.through sth.或carry sth.through。故carry out在本题更为合适。因此选D。