It is the first time that you have come to China, _____?

— I like football.— ______ my sister and me.

---Would you like me to carry the box?  ----_____.

.He said that not until the heavy snow blocked the express ______ how serious the weather was.

Another drug that has helped improve people’s health is penicillin, _________ is _________ by many _________ one of the most important medicines.