Table:
0
A
B
C
D
E
F
1
Year
1st Venue
2nd Venue
3rd Venue
4th Venue
5th Venue
2
2007
Sheffield
Mexico City
Nanjing
NA
NA
3
2008
Tijuana
Sheffield
Nanjing
NA
NA
4
2009
Doha
Changzhou
Sheffield
Tijuana
NA
5
2010
Qingdao
Veracruz
Veracruz
NA
NA
6
2011
Moscow
Beijing
Sheffield
Guanajuato
NA
7
2012
Dubai
Beijing
Moscow
Tijuana
NA

Questions and formulas:
Question: How many 5th venue cities were there when Doha was the 1st venue city?
Formula: ROWS(UNIQUE(FILTER(F1, B1="Doha")))
Formula2: ROWS(UNIQUE(FILTER(F2:F7, B2:B7="Doha")))
Level: medium
Question: When Qingdao was the 1st venue city, how many 2nd venue cities were there? 
Formula: ROWS(UNIQUE(FILTER(C1, B1="Qingdao")))
Formula2: ROWS(UNIQUE(FILTER(C2:C7, B2:B7="Qingdao")))
Level: medium
Question: In 2010, how many 1st venue cities were there? 
Formula: ROWS(UNIQUE(FILTER(B1, A1=2010)))
Formula2: ROWS(UNIQUE(FILTER(B2:B7, A2:A7=2010)))
Level: medium
Question: When Qingdao was the 1st venue city, who was in the 2nd venue?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:F1,B1="Qingdao"),3))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:F7,B2:B7="Qingdao"),3))
Level: medium
Question: What city was in the 3rd venue when Mexico City was in the 2nd? 
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:F1,C1="Mexico City"),4))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:F7,C2:C7="Mexico City"),4))
Level: medium