Smoking in public places is an offense to the law in Singapore.<br/><br/>Smoking in public is an offense to the law.<br/><br/>Smoking at public places......(wrong?)<br/><br/>Catch up with the rest of the class<br/><br/>Catch up in class/school (class refers to a classroom?)<br/><br/>Catch up with your class (class refers to classmates?)<br/><br/>Catch up with the teacher's lesson<br/><br/>Could you please tell me the mistakes in the above examples?