在制作人体口腔上皮细胞临时装片时，将标本放于下列哪一项中 [ ]
A．清水
B．糖水
C．植物油
D．生理盐水
D
I always have so many things to__________when I come back to the company after a trip abroad. [ ]
A. add to
B. contribute to
C. attend to
D. appeal to
简述在蛋白质生物合成中，三种RNA起什么作用？
