交通方便說"The traffic is convenient"是錯的!應該說...... 
  Sam上課遲到了,因為路上交通擁擠,脫口而出,他向外籍老師說:
  "I am sorry.The traffic was very crowded."(X)
  人群擁擠是crowded,很多人想當然爾,如法炮製。這句話的錯誤率很高,超過八成的學生都會這麼說。crowded是用來形容空間、地方的擁擠,像
  a crowded train(擁擠的車廂)
  a crowded city(熱鬧的城市)
  The meeting room is crowded with people.(會議室裡擠滿了人)
  原來不能用crowded形容traffic,Sam趕快改口用:"The traffic is jam."原來這麼講也不對。
  Jam可以當動詞或名詞,意思都是堵塞,但它不能當形容詞:
  A crowd jammed into the bus.(一群人湧上公車)
  We got into a traffic jam.(我們遇上了交通堵塞)(注意,遇上用got into,不是met)
  我們可以說"The traffic is jammed."意思又稍有不同,jammed是卡住了,"The traffic is jammed."指的是交通卡住了,動不了。
  形容交通擁擠,英文用heavy、much
Traffic is very heavy during the rush hour.(尖峰時間交通十分繁忙。)
  變化一下詞性,可以這麼說:
  This is the most heavily trafficked road in Taiwan.(這是台灣交通最繁忙的一條路。)
  形容交通擁擠,也可以用busy,但busy更常用來形容街道:
  The roads are busy (with traffic)(路上人來人往。)
  There is too much traffic on the street(這條街上車太多了。)
  相對的,不擁擠用light/little
When traffic is light, I can reach my apartment from the office in seven minutes.(交通順暢時,我辦公室到住家只要7分鐘。)
  There's little traffic at this hour.(這時候幾乎沒什麼車輛往來。)
  類似的錯誤,講到交通方便,很多人會說
  (X)The traffic is convenient.
  這麼說聽起來有濃濃的中文味,交通方便,一般指大眾運輸系統便利,可以換幾種說法:
  (O)The area has a good public transport network.(此區有很好的大眾運輸系統。)
  (O)There is good public transport.(交通便利。)
  Convenient不用來形容交通,但它可以用在指服務:
  It has a very convenient bus service.(這裡搭公車很方便。)