如:He was born on Monday, February 18,1995.(他出生在1995年二月十八日,星期一) / They usually plant trees on the hills in spring.(春天他们通常在山上植树) (4) (第一次使用)复数名词表示人或事物的类别时不用。如:Men are cleverer than monkeys.(人比猴子聪明) (5) 三餐饭前不用。如:We ...