____ 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.

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.

Smoke, dirt and noise are all kinds of ___.

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

Land erosion is normally caused by widespread _________.

Only a few of the many species at risk of extinction actually make it to the lists and obtain legal ____.

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

Are you sure that boys are more _______ than girls?

Advanced technology can last our _______.

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

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

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

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

It was such a boring speech that I felt _________.