1921年6月， * * 国际代表（）来到上海，考察中国的革命运动。
参考答案：马林
-- Our English teacher tells us that ______ grammar is a good way to learn English.
--And our teacher says _____ also helpful to sing English songs.
A．study, that was
B．is studying, it’s
C．studying, it’s
D．studied, that was
红外扫描仪
