lt is twenty four hour service so you can send e_meail at any time of the day or night的意思
主语从句，由that引导的主语从句，一般会放在句子后面，而用it做形式主语
（1）
Food is very important to our health.(1)EVERYONE needs to well if he or she (2)WANTS to have a strong body.Our minds,(3)LIKE our bodies,needs the best food. This (4)KIND of food is knowledge. We start getting knowledge when we are very (5)YOUNG.
Studying brings us the most knowledge. When we get older, we should (6)ENJOY reading and learning about all kinds of things. If we just accept answers without (7)THINKING about them,we never learn well, when wen study in the r(8)RIGHT way to get knowledge, we can learn (9)BETTER?你第一个字母没给 =） and understand (10)BETTER.
（2）
Dogs are very good pets. They are very (1)FRIENDLY people and very beautiful,too. Most dogs get on well with (2)CHILDREN and their parents.Others are good watchdogs because they cry loudly when a (3)STRANGE person arrives.
When you buy a bog , an important thing to think about is its (4)SIZE , buy a small dog if your home is small and a bigger one if (5)YOURS is larger. Many people don’t know what to feed their dogs.Dogs eat (6)ALMOST anyting! They like meat, rice and lots of other things. You can buy lots of food (7)MEAT for dogs in shops. Don’t let your dog eat too much. Feed it only once a day。Always (8)LEAVE some clean water for your dog. It can get (9)THIRSTY very quickly, especially in summer.
Remember that dogs need (10)EXERCISES. You should take it for a walk every day. Don’t keep your dog inside all day.
(3)
Are you able to send a letter with picture and sounds to someone anywhere in the world without putting a stamp on it? (1)WITH e-mail you can just do that. Using a (2)COMPUTER you can send e-mail quickly and easily. The post is much (3)SLOWER than e-mail. E-mail can send (4)INSTANT message to the other side of the world in second .
E-mail is easy to use and it (5)SAVES time andmoney. The differences in time in different parts of the world do not matter (6)WHEN sending e-mail. It is twenty-four-hour service that you can send e-mail at any time of the day or (7)NIGHT. No one has to be (8)THERE to receive e-mail. It (9)DOESN'T matter if your friends are in bed when you send e-mail to them, or you are seeing a (10)FRIEND at the cinema when they send e-mail back.
这是24个小时全天候的服务,因此您可以在白天或是晚上的任何时候发送邮件
24小时服务，所以你不论昼夜，任何时间都可以给我发邮件。
全天候服务，随时恭候！
