Mark Twain______ as a great thinker.[ ]
A.is known
B.isn't known
C.isn't know
答案:A
选择轮椅时,扶手过高容易引起()
A.身体前倾
B.推动轮环时擦伤上臂皮肤
C.轮椅后倒
D.心率减慢
E.血压降低
试论述旋转刹车油变质,怎样正确更换?