重金属检查中,如以硫代乙酰胺试液为显色剂,应控制最佳的pH是
A.2.5
B.3.5
C.6.5
D.9.5
E.11.5
参考答案:B
若i为虚数单位,对于实数a、b,下列结论正确的是()
A.a+bi是实数
B.a+bi是虚数
C.a+bi是复数
D.a+bi≠0
—Can you follow me?
—Sorry. I can ______ catch what you said. Could you say it again? [ ]
A. nearly
B. really
C. hardly