题干
—How many lessons do you usually have a day?
—Six lessons a day. And each of them _____45 minutes.
—Six lessons a day. And each of them _____45 minutes.
A：last
B：last
C：have
D：are
答案(点此获取答案解析）
B
2H2↑+O2↑．电解一定质量氢氧化钠稀溶液的过程中，下列说法正确的是