When Mark opened the door, he saw a woman standing there．He ________ her before．

A．never saw

B．had never seen

C．never sees

D．has never seen

Though he ________ four invitations, he ________ only one of them．

A．received; accepted

B．accepted; received

C．received; received

D．accepted; accepted

Charles Babbage is generally considered ________ the first computer．

A．to invent

B．inventing

C．to have invented

D．having invented

When he was young, he ________ a great interest in science．

A．developed

B．invented

C．made

D．discovered

Selecting a mobile phone for personal use is no easy task because technology ________ so rapidly．

A．is changing

B．has changed

C．will have changed

D．will change

－What’s wrong with your coat?

－Just now when I wanted to get off the bus, the man next to me ________ on it．

A．sat

B．had sat

C．had been sitting

D．was sitting

While watching television, ________．

A．the doorbell rang

B．the doorbell rings

C．we heard the doorbell ring

D．we heard the doorbell rings

________ from other continents for millions of years, Australia has many plants and animals not found in any other country in the world．

A．Being separated

B．Having separated

C．Having been separated

D．To be separated

The manager had fallen asleep where he ________, without undressing．

A．was laying

B．was lying

C．had laid

D．had lied

－If the traffic hadn’t been so heavy, I could have been back by 6 o’clock．

－What a pity!Tina ________ here to see you．

A．is

B．was

C．would be

D．has been