下列微粒符号中，对“2”的含义理解正确的是 A．2N表示2个氮原子 B．表示的化

任务型阅读（共10小题；每小题1分，满分10分）
Travelling is one of the most important activities and people have been interested in it for many years. Modern traffic develops fast, so travelling to different places has become much faster than before. Staying healthy while travelling can make your trip happier. But do you know how to keep healthy during a trip? The following information may be useful to you.
Before leaving
Wear comfortable shoes, a hat and sunglasses.
Take some necessary medicine with you. They can be used when you get sick or have other problems.
Do some exercise for weeks or months before you leave if you plan to do lots of walking or climbing during your trip.
Prepare proper (适当的)food. Before you prepare the food, the first thing you need to think about is how long you will travel with the food. If you take a long trip, you should bring food such as bread, biscuits and some fruit. They don’t go bad quickly. The nearer people can bring meat, fish, eggs, milk and even salads and vegetables.
While travelling
Be sure not to eat dirty food or bad fruit.
Have enough time to take a rest during your trip.
Tap（水龙头）water is not safe, so drink bottled water and always clean the cover of the bottle.
Keep food in good condition（状态）. If you take hot food, you should try to keep it hot. For example, you can put it in heavy towels（毛巾）. If you need to keep cold food cold, you can put cold food in a box with ice. When you arrive, put cold food in the fridge. Remember: If you travel with food, keep hot food hot and cold food cold.

How to keep (73) _________ during a trip
Before leaving	● Wear comfortable shoes, a hat and (74) ________.
	● (75) ________ some necessary medicine with you.
	● Exercise for weeks or months (76) ________ you leave.
	● Prepare proper food. Take bread, biscuits and some fruit for a(77) ________ trip or bring meat, fish, eggs, milk and even salads and vegetables for a nearer one.
While (78) _______	● (79) _______ eat dirty food or bad fruit.
	● Have enough (80) ________ to take a rest during your trip.
	● Drink (81) _______ water and always clean the cover.
	● Keep food in good condition. (82) _______ to keep hot food hot and cold food cold.