英文句型連接詞 when 的用法:如:Friction helps you when you ride your bike.;When friction is not helpful, we want to decrease it。by(藉由)的介係詞用法: We can decrease friction by making the rubbing surfaces smoother.;We can decrease the friction in the machine by putting oil or grease on the rubbing surfaces。以及用以詢問經驗的現在完成式疑問句用法:Have you ever tried to ride your bike in sand?;Have you ever noticed how smooth and shiny the surface of a playground slide is?。 寫作技巧,有Cause & Effect因果、Use Pronouns “you” & “we” to Engage Readers使用代名詞「你們」「我們」邀請讀者、Universal Ending Technique全體作結技巧。