I wonder if the doctor that answer my question can see my other (previous) questions?

Usually not. HealthTap BASIC free questions are displayed to many thousands of volunteer doctors who enjoy helping people. The questions are not grouped by HealthTap member (such as you). However, if you ask several questions on the same topic, one doctor might see 2 or 3 of them and guess that they are from the same member. That could happen by chance sometimes.