与产生X线强度无关的因素是
A．靶物质B．管电压C．管电流D．高真空度E．高压波形
参考答案：C
解析：管电流的大小与X线强度无关。
Daniel insisted that it _____ his fault that the house was a mess and that he _____ sorry to his parents. [ ]
A. should not be…should not say
B. was not…should not say
C. was not… mustn't have said
D. should not be… didn't say
甜菜基肥的施用量占施肥总量的70%～80%，采用（）或条施。
A、沟施
B、撒施
C、穴施
D、深施
