—Do you know ______ Tom was punished by his father?—That was ______ he refused to go to school.

题干

—Do you know ______ Tom was punished by his father?
—That was ______ he refused to go to school.

A：why; because

B：when; why

C：how; whe

D：why; why

上一题下一题 0.0难度选择题更新时间:2019-12-25 04:42:21

A

资料1：给动物刺激A，产生某反射活动；给动物刺激B，不产生该反射活动．如果同时给动物刺激A和刺激B，经过多次重复后，不给动物刺激A，只给刺激B也可以产生该反射活动．其中刺激A称为非条件刺激，刺激B称为条件刺激．

资料2：给大鼠服用药物C可引起抗体水平下降．给大鼠服用糖精则抗体水平不变．

若同时给大鼠服用药物C和糖精，经过多次重复后，只给大鼠服用糖精，结果引起抗体水平下降．

资料3：有些激素能够抑制免疫反应，有些激素则能够促进免疫反应．

资料4：食物中蛋白质缺乏导致严重营养不良时，动物的淋巴组织萎缩，免疫反应下降．根据资料回答下列问题：