He had no choice but to go on because it is their agreement that no one ______ quit the plan half way.

I am fond of my sister but she has one serious shortcoming. She _________ be really stubborn.

China’s word，tuhao，which caught the attention of the dictionary’s editing team，__________ be in next year’s Oxford English Dictionary．

——Must I park my car behind the building?——No, you needn’t. You _____ park it here. 

I have never heard______.