血液中能止血和吞噬病菌的血细胞分别是[ ]
A.血小板和红细胞
B.血小板和白细胞
C.白细胞和红细胞
D.白细胞和白细胞
答案:B
All this snow and ice makes it difficult for old people to ____ very well.
A.get around
B.go away
C.pick up
D.take off
根据黄连来源及产地的不同,商品上有味连、雅连和()之分。