10.Abouthowmanyelements____makeupmostofthesubstanceswemeetineverydaylife?
Abouthowmanyelements____makeupmostofthesubstanceswemeetineverydaylife?
A.itisthat
B.itiswhich
C.isitthat
D.isitwhich
用which,还是用that是怎么看的?
用itis,还是用isit是怎么看的?