cover

1.under separate cover作“在另一封袋里”或“在另一包里”解。例如：I send the book under separate cover. 在separate前面通常没有a。

有人以为under separate cover有些商业文件和公文气息，在一般通信里最好改用separately。

2.under cover of（靠着…的庇护，假托…的名义）和under the cover of都可以用。

3.注意下面各句里都用with，不用by。

• The ground is covered with snow.
• The trees are covered with flowers.
• The table is covered with books.
• His head is covered with grey hair.

4.Please write to me under cover to my father（请把你写给我的信，封在你写给我父亲的信里）里的cover前面不可加the。