If you do not know the subject, you will not understand what is said or written, even if English is your mother （） what is said or written.

A green building is （） to have reduced its environmenta...

单项选择题A green building is （） to have reduced its environmental impact by 60% compared with an equivalent conventional building.

A professional degree will （） an average annual income ...

单项选择题A professional degree will （） an average annual income of about twice that of college graduates.

The waiters will refill your coffee cup several times f...

单项选择题The waiters will refill your coffee cup several times for no extra（）.