题目

    It’s kind __________ Yao Beina to donate her corneas (眼角膜) _________ three people in need. A. of; to                B. for; to                      C. of; for                      D. for; for 答案：A闭合电路的一部分导体在磁场中做切割磁感线运动，导体中就会产生电流．这种现象叫做______现象，人们利用这个现象制成了______．