Just as one of the parents ____ it, students today are under far greater stress than ever.

A. says             B. speaks           C. puts                 D. gets

 He came running along and climbed ____ the train just as it was about to leave.

A. aboard           B. board                C. abroad           D. on abroad 

 Mike is Mrs.’ pet student, ____ all her students no one else is as nice as he.

A. because          B. because of           C. with                 D. as 

 Even though the pure water is ____ gives sea water its main properties, the salinity of sea water affects both its weight and freezing point.

A. the one          B. which                C. what                 D. that

 They find themselves surrounded by colorful rocks, fishes, seashells and plants, all ____ slowly in the blue water.

A. waving and moving  B. waved and moved

C. waved and moving     D. waving and moved

 They form a polar molecule, ____ is, ____ with a slightly positive end and a slightly negative end.

A. which; that      B. it; one          C. that; one            D. one; that

 But at other moments you will find him gentle and weak, _____ he cries about the lost lives of people drowned in ships that have sunk.

A. as with          B. as for       C. as to                D. as when

 He cut off the electricity immediately he found the dangerous situation, thus ____ a fire accident.

A. prevented        B. to prevent   C. would prevent        D. preventing

 My bicycle is nowhere to be found. Who ___ have been using it?

A. should           B. must                 C. could            D. might

 It is hoped that these new discoveries will throw ____ light upon such ____ mysterious natural phenomena.

A. a; a             B. a; /                 C. /; a                 D. /; /