This passage suggests that the successful exploration of the ocean depends on _________ .
A.vehicles as well as divers
B.controlling currents and the weather
C.radios that divers use to communicate
D.the limitation of diving equipment

The word “cruise” could best be replaced by ___________ .
A.travel at a constant speed
B.function without problems
C.stay in communication
D.remain still

With what topic is the passage primarily concerned?
A.Communication among divers.
B.Direct observation of the ocean floor.
C.Undersea vehicles.
D.Technological advances in oceanography.

Solar energy is considered as one kind of................ fuels.
A.alternative
B.various
C.replacing
D.changing

Applicants for government posts are always thoroughly ..............before being admitted.
A.supported
B.trained
C.investigated
D.helped

Someone must have taken my bag. I clearly remember................. helped it by the window and now it has gone.
A.leaving
B.leave
C.to have left
D.to leave

Mr. Brown................ for 10 years when he finally gave it up.
A.had been smoking
B.has been smoking
C.had smoked
D.has smoked

............... they might be hungry. I offered them something to eat.
A.To feel
B.Felt
C.Feeling
D.Having felt

The sun is shining and there are very few clouds; ................. , I am sure it is going to rain.
A.hence
B.nevertheless
C.what's more
D.thus

Dangerous chemicals can be ............. from burning plastics or hairspray containers.
A.freed
B.invented
C.released
D.escaped