--Why is the road so crowded?
--The two underground lines ________.
| A．are built | B．have been built |
| C．are being built | D．have been building |
Tell Mary that there's someone_______for her at the door.
| A．waiting | B．waited | C．waits | D．to wait |
Anything worth ______ is worthy of ______.
| A．doing, doing | B．doing, being done |
| C．being done, to be done | D．to be done, being done |
---Will the Smiths go abroad this summer?
---No, they finally decided _______.
| A．to | B．not going | C．not to | D．not to be going |
The patient was warned _______oily food after the operation.
| A．to eat not | B．eating not | C．not to eat | D．not eating |
Charles Babbage is generally considered _______the first computer.
| A．to invent | B．inventing | C．to have invented | D．having invented |