词汇：raise, several, skater, stamp, kite, monster, globe, store, coin, be interes ted in
Step 1: Revision
1. Show them a picture, ask: What’s he doing? (He is drawing a picture.)
Then show them: started 15 minutes ago, ask: How long has he been drawing the picture? Help Ss answer: He has been drawing the picture for 15 minutes/since 15 minutes ago.
