企源知识库

In making such models, skills as well as thorough knowledge of plant structure are ______.
A、called on
B、called up
C、called for
D、called in
【正确答案】：C
【题目解析】：call on呼吁，拜访，请求，号召； call up打电话； call for需要，要求；  call in召集，召来句意：在制作这样的模型时，需要技能以及对植物结构的全面了解。