Prf
n. pulse-repetition frequency的简 写
🗣️ 情景例句
What are you doing tomorrow night?
明天晚上做什么？
I know the boy whose father is a ball player.
我知道那个男孩的父亲是球员。
The little baskets were empty and the ground was covered with pieces of paper, cigarette ends, old tyres, empty bottles and rusty tins.
废物筐是空的，而满地都是纸片、烟头、旧轮胎，空瓶子和生锈的空罐头盒。