He spent at least as much time reading as you on line yesterday.A. had to chatB. do chatti

问题补充：

He spent at least as much time reading as you on line yesterday.

A. had to chat

B. do chatting

C. had chatted

D. did chatting

答案：

A. had to chat

B. do chatting

C. had chatted

(答案→)D. did chatting

解析：考察替代的形式。本题的did代替spent,第二个as是关系代词，代替time作为did(spent)的宾语，构成spend some time （in） doing sth花费时间做某事；故D正确。句意：昨天他花在阅读上的时间和花在网上聊天的时间一样多。