多项选择题 The teachers' development generally goes through three stages which are（ ）.A.taking teaching as their career (the need of survival)B.taking teaching as a sidelineC.taking teaching as their cause (the need of life)D.taking teaching as their profession (the need of lives)

判断题 涤纶具有良好的热塑性，会在不同的温度下产生不同的变形。

多项选择题 撰写投诉回函的四个步骤：Four steps of writing a letter of adjustment. A. Apology for the error of fault. B. A short explanation of the fault. C. Proposal to settle the problem. D. Acknowledge receipt of a complaint letter.