Although medical science ______ control over several dangerous diseases, what worries us is that some of them are returning.
| A．achieved | B．has achieved | C．will achieve | D．had achieved |
_____is today Britain used to be three different countries,and over many years the three countries became one.
A,It B,What C,Where D,As
At that time,it seemed _____I could not think of the right word anyhow.
A,even if B,in case C,as if D,in order
______is estimated that a round-trip to Mars would take more than a year.
A,That B,what C,There D,It
______leaves the room last ought to turn off the lights.
A,The person B,whoever C,Who D,Anyone
The reason why he was removed was ______he was careless and dishonest.
A,when Bbecause C,thatD,what