Teachers must put the brakes on,as it were,when they notice stude_英语解答

Teachers must put the brakes on,as it were,when they notice students looking puzzled.
请问这句话的语法结构如何理解?
look为什么要加ing?

人气：262 ℃　时间：2019-11-16 12:01:59

解答

put something on中的on是宾补as it were是插入语looking puzzled也是宾补宾补是在宾语后起修饰作用的之所以用look+ing是因为look在这里不能当谓语（主句是they notice students.其中notice是谓语,一句话中不能有双...