完成句子
The money was being ____________for their retirement.
他们把钱存着以备退休后使用。
How many factory workers are __________________losing their jobs?
有多少工厂的工人有失业的危险？
He was hit by a falling tree and killed___________________________.
一棵树倒下来，把他当场砸死了。
This old custom is ________________this year.
今年这个古老的风俗又时兴起来了。
She happened _____________a paper when I visited her.
我去拜访她时，她碰巧正在写论文。
Many species of wild animals are _________________extinction.
许多种类的动物处在灭绝的边缘。