在氯霉素滴眼剂处方中,下列物质的作用是
氯化钠()
A.渗透压调节剂
B.抑菌剂
C.抗氧剂
D.金属离子络合剂
E.pH调节剂
参考答案:A
It was so cold that they had the fire _____ all night. [ ]
A.to burn
B.burn
C.burning
D.burned
能一次性鉴别澄清石灰水、稀盐酸和食盐溶液的试剂是______.