Although international travel is usually an exciting and pleasant experience, travellers should take steps to ensure that their health does not suffer either from their time in the air or from their time abroad. BEFORE YOU GO Check with your doctor or local travel clinic which injections are necessary for the areas you are travelling to. Allow sufficient time to have these injections before you leave because they may take time to become effective. Be sure that the information on health is up-to-date. Check on the Internet if you are not sure. Don’t go to bed late the day before you fly. DURING THE FLIGHT 1. JET LAG Your body has a natural daily sleep pattern. It takes time to adjust to a new time zone. There are many different effects of jet lag: you may not be able to sleep, you may not want to eat or you may feel sick and tired. You may not be able to concentrate for some days after you arrive. There are several things you can do to lessen the effects of jet lag: － Do your best to relax during the flight; － Sleep as much as you can on the flight. Use a mild sleeping pill if necessary; － Drink as much water as you can; － Don’t drink alcohol and caffeine; － Take mild sleeping pills for the first few days in the new time zone if you need them. 2. DEEP VEIN THROMBOSIS (DVT) If you sit still for long periods of time, you will probably get swollen ankles and muscle cramps – these are painful but not dangerous. However, the much more serious DVT may also occur occasionally after long periods of inactivity — __________(1). This is not only true for air travel — it is the same for travellers by bus or train who spend many hours sitting in cramped conditions. To minimise the risk of DVT during the flight: - Stretch your legs and arms often while sitting in your seat; -_______________(2). Most importantly, if you have any worries about your health during the flight, call a flight attendant and tell them immediately how you feel. They will be able to help you. 1．What does the word “sufficient” mean in line 2 in Para. 2?