n.三十;三十个;三十年代;三十的记号;
num.三十;三十个;
例句:
In the thirties, air travel really began to take off.
在30年代,乘飞机旅行迅速流行了起来。
He's just a little over thirty.
他30刚出头.
He is thirty inches round the middle.
他腰围三十英寸.