Table: emission_standards
Columns: standard
date
co_g_kwh
no_x_g_kwh
hc_g_kwh
pm_g_kwh

Question: How many different standards have a PM of 0.02 g/kWh?
SQL: SELECT COUNT("standard") FROM emission_standards WHERE "pm_g_kwh" = '0.02'

Question: What's the HC for the Euro I standard?
SQL: SELECT "hc_g_kwh" FROM emission_standards WHERE "standard" = 'Euro I'

Question: What's the HC for the standard with NO x of 7.0 g/kWh?
SQL: SELECT "hc_g_kwh" FROM emission_standards WHERE "no_x_g_kwh" = '7.0'

Question: What's the PM for the standard with 12.3 g/kWh CO?
SQL: SELECT "pm_g_kwh" FROM emission_standards WHERE "co_g_kwh" = '12.3'

Question: What's the NO of the standard with HC of 1.23 g/kWh?
SQL: SELECT "no_x_g_kwh" FROM emission_standards WHERE "hc_g_kwh" = '1.23'