The eighteenth and nineteenth centuries _____ the widespread use of electricity and the birth of the steam engine , leading to the development of factories and cities.
| A．watched | B．observed | C．saw | D．showed |
It is the educational system, rather than the teachers, _______ is to blame for the students’ heavy burden nowadays.
| A．who | B．this | C．that | D．whom |
---- Did he come back early last night?
---- Yes. It was not yet eight o’clock _______ he arrived home.
| A．when | B．that | C．before | D．until |
After a few days together, they got to the point _______ they could read each other’s thought.
| A．which | B．that | C．where | D．when |
________ I want to know, sir, is whether you have any goods in that bag _______ I should know about.
| A．What; that | B．What; what | C．That; what | D．That; where |
The rate of racial progress varies in different areas of the country, but in the past ten years _________ more improvement.
| A．there is | B．it is | C．there have been | D．there has been |