boundary
单词辨析：
多指靠近两国或两地区分界线的区域。
the German-Polish border
德国与波兰边境
Two years later, he was sent to the border between China and Myanmar.
两年以后，他被派到了中缅边界。
侧重指某区域最外的界线，常和领土有关，也指地图上正式标定的、双方认可的边界或较小行政单位间的界线。
national/state/city boundary
国界/州界/市界
They marked the boundaries of the basketball court.
他们标出了篮球场的边界。
The river forms the boundary between my land and his.
这条河构成了我这块地和他那块地之间的分界线。
指两国接壤的前沿地区，多有军队驻防。
China has a frontier with Vietnam.
中国的边界和越南相接。
Soldiers guard the frontier against invasion.
战士们守卫边疆，防止外敌入侵。
相关例句：
Airplanes drag along a very thin shield of motionless air known as a boundary layer.
飞机曳着一层很薄的紧贴机面不动的空气一道向前运动，这层空气叫做附面层。
We investigate the characteristic boundary value problems for first and second order complex hyperbolic equations.
讨论了一阶和二阶双曲复方程的特征边值问题。
In this paper boundary integral method is generalized to solve the problem of bending of heavy camber cantalever beam.
采用边界积分法求解了大挠度悬臂梁的弯曲问题，给出了求解大挠度悬臂梁的解析解的新方法。
A river forms the boundary between the two countries.
一条河流成了两国的分界线。
The two neighbouring countries have at last reached an accommodation on their boundary problem.
那两个毗邻国家终于就边界问题达成了和解。
The boundary between Shanxi and Shaanxi is the Huanghe River.
山西和陕西以黄河为界。