A low wall built right across a river, so the water flows over the top of it instead of through it.

A low wall built right across a river一道直接橫跨河流建造的矮牆, so the water flows over the top of it instead of through it讓水從牆頂流過去，而不是穿過牆.

People build weirs to slow a river down, to keep the water upstream deep enough for boats, to measure how much water is passing, or to make a pool where fish gather and can be caught — that fish-trap use is the oldest one.

People build weirs人們建造攔河堰 to slow a river down為了讓河流變慢, to keep the water upstream deep enough for boats讓上游的水位深到船能通行, to measure how much water is passing或是用來測量流過的水量, or to make a pool where fish gather and can be caught或是做出一個魚會聚集、可以被抓到的水池 — that fish-trap use is the oldest one這種捕魚的用途是最古老的.

A weir is not the same as a dam: a dam is tall and holds the water back, while a weir is low and lets it spill over the edge in a smooth sheet.

A weir is not the same as a dam攔河堰跟水壩不一樣: a dam is tall and holds the water back水壩很高，把水擋住, while a weir is low and lets it spill over the edge in a smooth sheet而攔河堰比較矮，讓水像一片平滑的水簾漫過邊緣.

You see them a lot in Britain and Ireland on gentle rivers running through towns. It is a fairly quiet, countryside sort of word — not one you hear in daily conversation unless you live near a river.

You see them a lot in Britain and Ireland你在英國和愛爾蘭常常看得到它們 on gentle rivers running through towns那些流經城鎮、水流平緩的河上. It is a fairly quiet, countryside sort of word這個字算是相當安靜、鄉間味的字 — not one you hear in daily conversation unless you live near a river除非你住在河邊，不然日常對話不太會聽到.

Warning: the water below a weir looks calm but turns over and over, and swimmers get pulled under, so British people talk about weirs as dangerous places.

Warning注意: the water below a weir looks calm攔河堰下方的水看起來平靜 but turns over and over但其實會不斷翻攪, and swimmers get pulled under游泳的人會被拖到水底下, so British people talk about weirs as dangerous places所以英國人會說攔河堰是危險的地方.