1. _______ belching is socially unacceptable in many cultures, it plays a useful role in the digestive process.

2.  The liquid must be heated slowly _______ avoid sharp variations in temperature

3. _______ campaigns urging safe sex, the AIDS virus appears to be spreading among US males in their teens and early twenties who have had homosexual encounters.

4. Sex hormones are less effective when taken orally _______ some are absorbed by the liver; injected hormones bypass the liver so remain potent.

5. The company wants to separate larger quantities of the fluid _______ they can conduct a research and clinical testing programme aimed at gaining FDA approval.

 6. The experiment is not dangerous _______ the instructions are carefully followed.

7.  _______ progress in medicine, many different kinds of cancer can now be cured.

8.  Vaccination programmes are used _______ prevent disease spreading.

9. In women, the loss of calcium generally begins at age 40 _______ it rarely starts before 60 in men.

10. The pro-life lobby contests the use of aborted fetuses _______ they believe abortion is never justified.

11. Several skeletal muscles are antagonist — one contracts _______ another relaxes and extends.

12.  _______ pro-lifers think, abortion is sometimes necessary.