【单选题】He paid for and was assigned a cabin in first class. 句中划线部分的意思是
【单选题】已知D:|x|+|y|≤1,D1:x≥0,y≥0,x+y≤1,I= (|x|+|y|)dσ, J= (x+y)dσ,则( )。
【单选题】He worked his ________to Australia, and paid for the journey by doing jobs on the ship he was travelling on. [ ]
【单选题】What did the customer discover?
A.
He has already paid for the order.
B.
He was charged twice for the same product.
C.
The delivery company delivered the item to the wrong address.
D.
The book is out of print and no longer available.
【单选题】现代科学技术的发展,使()侦察监视水平有了极大的提高,利用现代高性能的侦察和监视系统可以实现全实时全空域的侦察和监视。
【判断题】正弦量可以用相量表示,因此可以说,相量等于正弦量。()
【单选题】已知|x|=4,|y|=5且x>y,则 的值为( )
【判断题】热线式空气流量传感器有了自洁功能后,热线部分便不易被污染。
【多选题】. 下列分组哪些是按品质标志分组 ( ).