配制20%的NaOH溶液100克,须称取多少克纯度为42%的NaOH溶液?
参考答案:
设需称取X克42%的NaOH溶液,则
20%×100=42%X
Allan cut the big birthday cake _____ small pieces. [ ]
A. as
B. to
C. into
D. in
需夜间检查诊断的寄生虫病是()
A.丝虫病
B.疟疾
C.旋毛虫病
D.血吸虫病