题干
---Tom hurt his left leg in the game this morning.
---Really? It would take at least two weeks ______ he could recover and return to school.
---Really? It would take at least two weeks ______ he could recover and return to school.
A：whe
B：that
C：since
D：before
答案(点此获取答案解析）
D
0 mol碳酸钠的溶液和200 mL盐酸，不管将前者滴加入后者，还是将后者滴加入前者，都有气体产生，但最终生成的气体体积不同，则盐酸的浓度合理的是