主動被動
主動與被動的判斷是動詞中很重要的觀念，通常我們可以借助下列三個線索來判斷主動被動：
1. 若動詞後有名詞片語(NP)，則幾乎都用主動語態，即“S+ V+ NP”，但consider(認為)，call(稱呼)及name(命名)例外，這種動詞可能用被動。
例：1. Hundreds of people visit the Washington Monument(華盛頓紀念碑) every day. (the Washington Monument為NP，請注意，凡是由冠詞、所有格、數目字所引導的片語皆為名詞片語。)
2. We consider him an artist.
3. He is considered an artist.
2. 若動詞後面有by，且by表達“被”、“由”，則用被動語態，但by若表達“藉著”、“在‥之旁”、“到‥為止”，則要拉主詞跟動詞的意思，才能判斷主動或被動。
例：1. The Old Man and the Sea was written by Earnest Hemingway.
2. He passes by the park every morning. (從‥旁邊)
3. He passed the examination by studying hard. (藉著)
4. I shall have lived in Taipei for 10 years by next week. (到‥為止)
3. 若動詞後沒有NP，也沒有by，則需利用主詞與動詞語意上的關係來判斷主動或被動。
例：1. The house was built in 1940.
2. The plan was carried out successfully.
3. Many people enjoy working at night.
此外，要特別注意有些動詞只用主動語態(常考的有happen, occur, take place“發生”，exist“存在”，die“死”，cost“價錢是‥”，rain, appear, seem, belong to , consist of“由‥組成”等)，另外有些則用於被動語態，如be exposed to(暴露在‥之下)，be supposed to(應該)，be located(位於)等等。
例：1. The idea appeared to me in my dream.
2. Dinosaurs(恐龍) existed millions of years ago.
3. The book consists of fifteen chapters.
