A．Two fifth; isB．Two fifth; areC．Two fifths; isD．Two fi……

单项选择题It is essential that these application()forms back as early as possible.

A．must be sent
B．will be sent
C．are sent
D．be sent

单项选择题Someone is knocking at the door. It () my mother. It's time for her to be back.

A．can he
B．may not he
C．must be
D．mustn't be

单项选择题Nobody but Jane () the secret.

A．know
B．knows
C．have known
D．is known

单项选择题My postcard is still on the desk. Why () you () it

A．haven't; posted
B．didn't; post
C．wasn't; posting
D．won't; post