Mohon dibantu yg nomer satu, TERIMA KASIH

a. I've lost the bag which/that i bought last week.
b. the house where Mr and Mrs Suyoto live is very old.
c. Jacob has gotten himself into a dangerous situation (over) which/that he has no control (over).

note: untuk yang C, overnya bisa ditempatkan sebelum which atau di akhir kalimat.