You must enter avalid credit card number

You must enter avalid credit card number You must enter a valid PIN You MUST enter a vaild email address. You must enter a valid birthdate. you must enter a name and a you must ____(knock)on the door before you enter you must enter your real first and last you must enter a valid e-mail address什么意思 You must enter a valid e-mail address 是什么意思 you must be at least tevel 19 to enter You must enter a name yo continue with installation you must enter at least one of the followong:wmail You must enter the room password. 中文什么意思 You must show your r_____ card when you enter the library You must enter a valid 5 digit zip code if you live in the United States. Before you enter the teachers office ,you must (k ) on the door first. You must enter a valid address.这个是什么中文意思?有助于回答者给出准确的答案 must ask(a,an,无)permission before you enter the room选哪个