伦常<书>moral principles

平常；通常ordinary; usual

• 习以为常

  become accustomed to

不变的constant

• 四季常青

  evergreen

时常frequently

• 常来常往

  have frequent contact with somebody

• 不常

  seldom

• 我们之间常有争吵。

  We quarrel constantly.

• 这是常有的事儿。

  This is a frequent occurrence.