So far there is no proof ______ spaceships from other planets do exist.
A.which
B.that
C.how
D.what
The passage tells us that proof of life on Mars would ______.
A.make clear the complex chemistry in the development of life
B.confirm the suggestion that bacterial fossils traveled to Earth on a meteor
C.reveal the kind of conditions under which life originates
D.provide an explanation why life is common in the universe
From the passage, we can not find the proof of the fact that ______.
A.now mothers do their household work just as well as they did before
B.with their mothers working, children are better off
C.lack of mothers' care, children like to go astray
D.in single-parent families, most children like their mothers go out working
A.write a firm letter of complaint to the store of purchase
B.show some written proof of the purchase to the store
C.complain personally to the manager
D.threaten to take the matter to court
Then the()of immigrants became a stream, and the population began to move ()- not to grab and () but to settle and (), they thought. The () were of peasant (), and they had their () in a Europe ()they had been (), for the possession of land was the requirement and the ()of a higher social class than they had known.
A.与安慰剂相比,鲑降钙素100IU能明显降低对非椎体骨折风险
B.与安慰剂相比,鲑降钙素100IU能明显降低新发椎体骨折风险
C.与安慰剂相比,鲑降钙素200IU能明显降低新发椎体骨折风险
D.与安慰剂相比,鲑降钙素200IU能明显降低非椎体骨折风险