New medicines and instruments ______ every day to extend life.
| A．develop | B．are being developed |
| C．are developing | D．have developed |
Evidence has been found through years of study _____ children’s early sleeping problems are likely to continue when they grow up.
| A．why | B．how | C．that | D．whether |
The singer’s flight was _____ due to bad weather, resulting in the show _____.
| A．put out; to be canceled | B．put off; to be canceled |
| C．put out; being canceled | D．put off; being canceled |
As the family did not make a(n) _____ ahead of time, they had to wait at the restaurant in order to get a table.
| A．approval | B．reservation | C．arrangement | D．enquiry |
Some people hold the view that the new machine is advanced, while others are still skeptical _____ whether it is of practical use.
| A．with | B．about | C．for | D．on |
According to the engineer, there remain some tests _____ before the machine is put into operation.
| A．carrying out | B．carried out | C．being carried out | D．to be carried out |