公元前622年，穆罕默德在麦加建立了政教合一的国家。伊斯兰教把公元前622年定为伊斯兰教教历元年。 （   ）

    We live in the computer age. People use computers to do much of their work. But few people know how to look after them. Remember the following when you use your computer:
    ① Keep your computer in a cool ,dry room. Too much or too little heat is bad for computers. Damp (潮湿) is also bad for them.
    ② Do not let people smoke near your computer. Smoke of all kinds is very bad for many parts of a computer.
    ③ Do not eat or drink when you are near your computer. Pieces of food and a little water in the keyboard are also bad for a computer.