____ is a branch of Natural Science, and is the study of living organisms and how they interact with their environment.

A/ an ____ species is a population of an organism which is at risk of becoming extinct.

They had a ______ dinner last night and she accepted his proposal of marriage.

Advanced technology can last our _______.

If a boss wants to have a well-qualified staff, he should have to pay his employees _______.

Children who are isolated and lonely seem to have poor language and ________.

As an _______, Mr. Pike is very worried about the increasing of juvenile delinquency.

It was such a boring speech that I felt _________.

Land erosion is normally caused by widespread _________.

He is not really friendly and makes no attempt to be _______.

Choose the best answer to complete the following sentences.

People should be told about the things that threaten the safety of ____ so that they can avoid doing them.

He has been very interested in doing research on _______ since he was at high school.

My mother used to be a woman of great _______, but now she gets old and looks pale.

My parents will have celebrated 30 years of _______ by next week.

Are you sure that boys are more _______ than girls?

The more _______ and positive you look, the better you will feel.