______children are in the picture.A．OneB．TwoC．Three

There are ______ Russian（s) and ______ American（s) on board.A．one, oneB．one, twoC．two, two

The three children looked after their sick mother______.A．in returnB．by turnC．in turnD．in

Two of the children have to sleep in one bed, but the other three have ______ ones.A．simil

In the lower 48 states in the USA, the top three largest national parks are______.A．Evergl

The word "unhappiness" has______morphemes.A．oneB．twoC．threeD．four

There is（are)______morpheme（s)in the word "non-smoking".A．oneB．twoC．threeD．four