生孩子难，养孩子更难。单就说幼儿流口水的事吧，这可是令父母们十分头痛的问题，常常一天要换几次衣服，用几条手帕，那么幼儿为什么总流口水呢？快来看看下面的解释吧。

Salivais produced by the salivary glands. There are three pairs of big salivary glands and countless small salivary glands distributed on our lips, cheeks, palates and some other places. The major part of saliva is water. Saliva also contains someamylasesand sticking proteins. Saliva moistens the oral cavity, helping us swallow and digest. Tests show that a normal adult secretes 1000-1500 ml of saliva in a day. Under normal circumstances, people swallow the saliva consciously and unconsciously.

Because newborn babies' saliva secreting functions are not perfect, they generally don'tslobber. After four months, because of the increase in food intake, babies secrete a little more. In six months, they begin to teethe. Thegingivalnerve is stimulated and reflectively increases the secretion of the salivary glands. At this time, children have not yet formed the ability to properly swallow saliva, and so the excess saliva will 'drool' out of the corners of their mouths. This is the most obvious in one and two year olds. As children grow older, their saliva-swallowing abilities will improve, and the slobbering will stop.

Saliva can be acidic, so it can stimulate the skin. Parents should often wipe saliva for children; wash the skin with warm water and then use lotion to protect the skin of children's chins and necks. The handkerchiefs used to wipe the saliva should soft enough not to damage partial skin.

saliva: 口水

amylases: 淀粉酶

slobber: 流口水

gingival: 齿龈的

（北京林业大学通讯员黄典钰供稿 英语点津 Annabel编辑）