Ten tasks mixing the beginner skills. None says which function to use: read it, look at the tables in the Explorer, and choose.
Keep the BigQuery habits in mind: every table needs its dataset, dates go first in date functions, LIKE is case-sensitive, NULLs sort first, and the SAFE functions keep one bad row from stopping a query. Each answer is also checked against a second copy of the data with different values, so write the rule, not the answer.