"do you know our town at all?" "no,this is the first time i ____here

"do you know our town at all?" "no,this is the first time i ____here
A)was
B)have been
C)come
D)are coming
请帮我翻译一下,为什么要the first time后面要用完成时态
2)we went to the exhibition yesterday_________
A)by a car
B)by cars
C)in a car
D)on a car
请说明选择理由,为什么不能选A或B