用单词的适当形式填空。 1. It was difficult  ________(build) the railroad for us. 2. What's ________ (he) name ? 3. Are those ________ (girl) your ________ (classmate) ? 4. He ________ (wave) to me and smiled . 5. The British ________ (bridge) are very nice . 6. We ________ (not,have) chicken but fish for lunch yesterday. 7.  —How long ________ it ________ (take) you to finish your homework last night? —Tow hours. 8. Yang Liwei is the ________ (one) astronaut of China. 9. These ________ (hero) are from Africa. 10. They ________ (build) the railroad five years ago.