我国西北最重要的铁路枢纽是（）市，有（）四条铁路交汇。
参考答案：兰州；陇海、兰青、兰新、包兰
用所给动词的适当形式填空。
1. It______(be) my birthday next Sunday.
2. They'll have a trip to the Great Wall if it ______(not rain) tomorrow.
3. Would you mind ______(help) me with my Chinese?
4. When I woke up, my parents ______(go) out.
5. Remember ______(not fight) with each other from now on.
最著名的死锁避免算法是______算法。
