Tom ( ) into the house when no one ( ).

Tom ( ) into the house when no one ( ).
a.slipped,was looked
b.had slipped,looked
c.slipped,had looked
d.was slipping,looked
I don't really work here; I ( ) until the new secretary arrives.
a.just help out
b.have just helped out
c.am just helping out
d.will just help out
He knew I collected stamps and coins and asked me whether my collection ( ).
a.was growing
b.was grown
c.grew
d.had been grown