学校文化建设有多个落脚点，其中课堂教学是学校文化建设的主渠道。在课堂教学中，教师必须

— Who should be responsible for the accident?

— The boss, not the workers. They just carry the orders _____. [ ]

A. as told

B. as are told

C. as telling

D. as they told

—Is chemistry more difficult than physics? 

— No, chemistry isn't as _____ as physics. [ ]

A. easy

B. difficult

C. easier

D. more difficult

In spite of these unexpected difficulties, the Chinese scientists ________ to carry out their experiments

on the lonely island. [    ]

A. threatened  

B. managed

C. offered  

D. hesitated

巷道发生底鼓，说明是底板承压水压力过大，一定会发生底板突水。