Is it my appearance the professor minds?——I guess not. He will consider necessary to have an experienced assistant.

It is said that the gravity on Mars is only about __________ of the gravity on earth．

Ms.Black is considered a ________ lady by her neighbours, for she often helps the poor old man next door.[ ]

What does Jack do in that company—— I’m not sure. He ________ be a salesman.

When you are learning a foreign language, _______, you must forget your own language