撤消防护的显示方法为()
A、一长两短声
B、两长一短声
C、一短一长声
D、一长一短声
参考答案:D
Choose and correct. 选出下列句子中错误的一项,并改正。
( ) 1. How many is the ball?
A B C D
( ) 2. —Can I use your pencil? —Here!
( ) 3. —Thank you! —You welcome.
( ) 4. How many peach can you see?
( ) 5. These apple are very nice.
休止角表示微粉的()
A.粒子形态
B.流动性
C.疏松性
D.摩擦性
E.流速