Table:
text: Masahiro Shimizu
Motorcycle Grand Prix Results
Motorcycle Grand Prix Results
Year_ Class_ Team Points Rank_ Wins
1987 250cc Honda 20 13th 0
1988 250cc Honda 68 10th 0
1989 250cc Honda 116 6th 0
1990 250cc Honda 100 7th 0
1991 250cc Honda 142 5th 0
1992 250cc Honda 46 9th 0

Question: What are Masahiro Shimizu's lowest wins with points greater than 46 and a rank of 10?

Question: What year is Masahiro Shimizu's point average, with a year higher than 1989 and a rank of 7?

Question: What year does Masahiro Shimizu have more than 20 points?

Question: Which year has points greater than 46 and a rank of 6 for Masahiro Shimizu?

Question: What was the earliest year with points greater than 68 and a rank of 7 for Masahiro Shimizu?