请教老师几道高二英语选择题 1 Do you mind if I record your lecture ? ( ) G

请教老师几道高二英语选择题 1 Do you mind if I record your lecture ? ( ) Go ahead.
A Never mind B No way C Not at all D No.You 'd better not
2 They have ( ) that any faulty parts will be replaced free of charge.
A guaranteed B promised C ensured D protected
3 John insisted that what he said ( ) true and we insisted that he ( ) and have a look.
A be;should go B should be ;would go C was ;go D was ;would go
4 ( ) the tempreature falling so rapidly ,we couldn't go on with the experience .
A Since B With C As D For
请老师帮忙详解,谢谢!