各种产生扭转变形的构件,其在变形方面特点是受扭转构件的各横截面都绕杆轴线发生相对转动。
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[τ]称为材料的许用剪应力,可由试验并考虑安全系数,也可按材料的许用拉应力[σ]的大小。二者之间有一定关系。
A. 对
B. 错
There are three_______ on the desk.
A. oranges
B. orange
C. an orange
D. a orange
The book is very _____. I’ve read it twice.
A. interest
B. interested
C. interesting
D. interests
Can I _______ your order now?
A. make
B. like
C. have
D. take