问题补充：
It last week that the haze(雾霾) in Beijing caused many problems.
A. reports
B. reported
C. is reported
D. was reported
答案：
A. reports
B. reported
C. is reported
(答案→)D. was reported
解析：句意：--上周据报道北京雾霾引起了很多问题。it it reported 据报道.... 因为有 last week所以要用一般过去时。故选D.
