The primary purpose is to _____ those achievements in biological research _____ the public.
A. make; known by B. make; known to C. make; know to D. make; knowing by
____ new cure for this disease that medical experts have recently developed proves to be ______ most effective, although it can not completely kill all the viruses.
A. A; a B. The; / C. /; the D. A; the
— What made your skin look so terrible?
— _______ to the sunlight for a long time.
A. Because it was exposed B. After being exposed C. Being exposed D. Exposed
Only after a baby seal is pushed into the sea by its mother _____ to swim.
A. how will it learn B. will it learn how C. it will learn how D. and it learns how
As is well known, carelessness and irresponsibility _______ many deadly accidents.
A. lead to B. result from C. contribute to D. result in
They ___________ for two hours
A. is working B. worked C. have been working D. had worked
