be thirty for：三十
例句：
1.The number of workers in each group must not be over thirty.
每组的工人人数不得超过30人。
2.I shall be thirty next year.
明年我就三十岁了。
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3.His period of pain was to be thirty-thousand years.
他的痛苦要持续三万年。
4."They tend to be thirty-somethings, slightly mature, with some kind of businessconnection to China, " he said.
“他们往往是30多岁，稍成熟，与中国有着某种商业联系，”他说。
5.She can't be thirty. Her mother is only forty.
她不可能有三十岁，她的母亲才四十岁。
