16．______, a man who expresses himself effectively is sure to succeed more rapidly than a man whose command of language is poor.
A．Other things being equal  B．Were other things equal
C．To be equal to other things  D．Other things to be equal

17．As early as 1647 Ohio made a decision that free, tax-supported schools must be established in every town ______ 50 households or more.
A．having  B．to have
C．to have had  D．having had

18．The car ______ halfway for no reason.
A．broke off  B．broke down
C．broke up  D．broke out

19．“Need we work late today?” “No, but we ______ tomorrow.”
A．need  B．must
C．can  D．ought to

20．______ might be expected, the response to the question was very mixed.
A．As  B．That
C．It  D．What