配制一定质量分数的食盐水,不需要使用的仪器是[ ]
A.玻璃棒
B.烧杯
C.药匙
D.量筒
答案:C
It’s hard to finish the work in a day. You’d better ____ your friends to help you.
A.call for
B.call on
C.call at
D.call up
超声能量在下列哪种组织的衰减最小()
A.肺
B.肌肉
C.肝
D.脂肪
E.血液