______ 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
