单项选择题
When his advertisement using the new digital technique drew as many as 5,000 responses overnight, he knew he ___________. A. was up to something B. was in something C. was onto something D. was on something
单项选择题 偏头痛的临床特点,以下说法正确的是( ) A. 多为偏侧头痛 B. 多为胀痛 C. 不会出现双侧头痛 D. 以上均正确
单项选择题 设A,B为随机变量，我么构造随机过程,其中A,B具有零均值以及相同的方差,且不相关，则X(t)的均方值为
判断题 ( )18Cr4V是属于钨系高速钢,它耐热温度可达600℃。
