26.Even if there is no scientific proof
题型:选择题
问题:
26.Even if there is no scientific proof yet ______ secondhand smoke causes cancer, there is no reason why nonsmokers should be forced to take this risk.
A.which
B.that
C.when
D.Where
26.Even if there is no scientific proof yet ______ secondhand smoke causes cancer, there is no reason why nonsmokers should be forced to take this risk.
A.which
B.that
C.when
D.Where