Eye contact is an important aspect of body language. One could draw up quite a lot of 'rules' about eye contact: to look or not to look, when to look and how long to look, who and who not to look at, etc.

眼睛会说话。你知道这些眼神的含义吗？
gaze - means to direct your eyes towards something for a long time.
stare - suggests to fix your eyes on somebody or something very deliberately. It can be impolite to stare at somebody.
peer - means to look very closely and suggests that it is difficult to see well.
gawk - is often used to show disapproval and means to look at someone or something in a foolish way especially with your mouth open.
glance - to take a quick look at something.
peep - means to look at something very quickly, especially secretly or quietly.
inspect - means to examine something closely.
feast your eyes - to look at something because you are pleased to see it.

在中国，如果两个陌生人相遇，比如两个人同坐一张桌子吃饭，一般两个人都会相互看一眼，而后或进行简单交流，或各自埋头吃饭。The usual response is to behave in a friendly and natural manner, glancing at the other person, perhaps saying 'hello' and exchanging small talk or remaining silent. 最好不要故意装作看不到对方，因为这样你会给人局促不安的感觉，对方甚至会怀疑你心中有鬼。If you try hard to avoid the other's glance or you look out of the window as if nobody sat nearby, you would appear so uneasy and so unnatural that you might lay yourself open to suspicion!
在聆听他人讲话的时候，to look at somebody, no matter whether he is senior or junior to you, while listening to his instruction is a sign of showing respect in China. 你不必总是盯着讲话的人，但是如果说话的人在看你，你应该以自然的眼神回应对方。To gaze intently may show your attentiveness, but is not that necessary. The best way is to look at him or her as naturally as he or she looks at you.

当众发言的时候，许多中国人羞于和听众进行眼神的交流。 Some of them, perhaps because of nervousness, like to bury their nose in their manuscript to read their speech all the time. 这种做法其实是不礼貌的。 Speaking in public is also a kind of two-way communication, which needs eye contact from both sides. The speaker will certainly feel embarrassed when he sees that his audience do not look at him. But if he doesn't look at his audience now and then, his audience also has the right not to listen to what he is saying. 如果你发言的时候没有勇气看听众，那么你也无权要求你的听众会和你形成良好的互动。

在英国，眼神的运用会有不同的地方吗？
在英国，如果你路遇陌生人，你要做到既不盯着对方打量，也不完全忽视对方。这个尺度该怎么拿捏呢？You may look at the approaching strangers until they are about eight feet away, then your glances must veer away as they pass.
与人交流的时候，British practice expects eye contact, though this does not have to be constant.
当众发言的时候，a British lecturer should look at his audience now and then. 他们是不会把脑袋埋在稿子里面说话的。