酸性条件下，可用某些盐溶液吸收水煤气中的少量H₂S，以回收硫元素、降低污染．欲达到该目的，下列试剂中最合适的是（　　）

设集合A={1，2，3}，B={2，4}，则A∩B=____ 

- Did you see _______ at the door? There is a boy waiting for you.        

- No, I saw_______.

— Oh, my god! My wallet is gone.

一 Where did you put it? Maybe you just left it somewhere.