题干
—What colour __________your shoes?— __________ black.
A：is; It's
B：is; Its
C：are; Their
D：are; They're
答案(点此获取答案解析）
D
—What colour __________your shoes?— __________ black.
A：is; It's
B：is; Its
C：are; Their
D：are; They're
+O2 +4OH－=Fe3O4+S4O62-+2H2O，下列说法正确的是（ ）
