______ a phone is of great help, I don’t think it’s a good idea to spend too much time on it.
A.If B.While C.Because D.As
Peter will come to understand your efforts sooner or later. It’s just a matter of _____.
A.luck B.value C.time D.fact
Experts think that __________recently discovered painting may be ________ Picasso.
A.the ;不填 B.the; a C.a ;the D.a ; 不填
It is not clear ____the effects of global warming will be.
A.how B.which C.that D.what
All the scientific evidence ______ that increasing use of carbon dioxide ______ the rise of the earth’s temperature.
A.show; result in B.shows; result from
C.shows; results in D.shows; results from
Without the ‘ greenhouse effect’, the earth ____ be about thirty-three degrees Celsius cooler than it is.
A.should B.would C.will D.must