作者：刘世一
1. 【原文】 How can you tell they are grateful? (L. 57)句中tell译为"告诉"句意好像不通，应该是什么意思？
【精析】 tell在此处不是"告诉"的意思，而是"判断；识别；区别"的含义。当tell与can, could, be able to等表示能力的情态动词连用时，强调辨别的能力，常用于tell sth. from sth. 结构，也可以直接跟宾语从句。例如：
Can you tell Gorge from his twin brother? 你能把乔治和他的双胞胎兄弟区分开吗？
Can you tell which answer is correct? 你能判断出哪个答案是正确的吗？
2. 【原文】 To help animals is helping people. (L. 57)请分析一下本句的句子成份。
【精析】本句是主系表结构。To help animals是不定式短语作主语，helping people是动名词短语作表语。不定式短语作主语可以用it来代替，将真正的主语放在句末。如本课中的But isn't it more important to help people than animals? 句中to help people than animals是真正的主语。
3. 【原文】 Mostly, vets helped heal horses.... (L. 58)heal与本课中的treat都有"治病；治疗"的意思，有什么不同？
【精析】 heal主要指通过治疗，而恢复健康。如：
A doctor's duty is to heal the sick.医生的职责是治病救人。
treat是个普通的用语，指接受病人，替他诊断，治病。如：
Doctors treated the patient very carefully. 医生认真地为病人治疗。
4. 【原文】 ... but the house broke in two, dropping her to the first floor and leaving the baby's bed hanging on the edge of the two-story house. (L. 60)请分析本句的句子结构。
【精析】 broke是谓语动词，三个分词短语作伴随状语，其中dropping her to the first floor and leaving the baby's bed是说明谓语动词broke的具体动作，hanging on the edge of the two-story house则是用来说明leaving的具体内容。