一、第一句
原句：May I have your attention, please？ Always do as the teacher tell you to. Change your shoes before entering the lab.
错误分析：
1. 动词时态错误：第二句中"tell"应改为"tells"，因主语"teacher"为单数，需用第三人称单数形式。2. 介词使用不当：第三句中"before enter"应改为"before entering"，需用动名词形式作"before"的宾语。 修改后：
May I have your attention, please？ Always do as the teacher tells you to. Change your shoes before entering the lab.
二、第二句
原句：The movie was really exciting.
错误分析：
1. 形容词使用不当："exciting"用于描述事物本身令人兴奋，而此处应表达"令人兴奋的"感受，需用"excited"（形容人）。 修改后：
The movie was really exciting. → The movie was really exciting.
三、第三句
原句：She has a lot of money.
错误分析：
1. 量词使用不当："a lot of"修饰可数名词复数时需加"s"，而"money"为不可数名词，应直接用"lots of"或"a lot of"。 修改后：
She has a lot of money. → She has lots of money.
补充说明：
改错时需注意主谓一致、动词时态、介词搭配等基本规则。例如：
主谓一致：
"The students have finished their homework"（复数主语用复数谓语）
"He asked me where I’d like to go to"（"where"引导宾语从句时，谓语用过去时）
动词形式选择：
需用现在分词（如"walking"）作后置定语时，需用"be+现在分词"结构（如"a walking man"）
建议结合具体语境分析错误类型，逐步掌握语法规则。