问题

The students listened carefully to the teacher with their eyes _____ on the blackboard.

A:focused
B:to focus
C:focusing
D:being focused

正确答案是：

同类题型

Mr. Fox fell ill, thus __________ it necessary for us to find another person for his job.

_________has Joe been playing baseball— Since he was ten years old.

一Whose T-shirt is this Is it Sally’s—No, it isn’t. _______ is white.

Paul, stand ________ your feet.

He enjoys ______ books.