According to economic theory, a nation should produce and export those items （）it gains a competitive advantage.
A.正确答案Afrom which
B.for that
C.by what
D.about it
According to economic theory, a nation should produce and export those items （）it gains a competitive advantage.
According to economic theory, a nation should produce and export those items （）it gains a competitive advantage.
A.正确答案Afrom which
B.for that
C.by what
D.about it
