只用一种试剂就可区别Na2SO4、AlCl3、NH4Cl、MgSO4四种溶液。这种试剂是[ ]
A.HCl
B.BaCl2
C.AgNO3
D.NaOH
答案:D
丝绸之路是汉代中外交流的见证。图7中①所示中国通往南亚、中亚的交通要冲是
A.葱岭
B.玉门关
C.大宛
D.安息
Daniel and I ______ in Class1, Grade 7. ______ are classmates. [ ]
A. am, They
B. am, We
C. are, We
D. are, They