Modal auxiliary (can,may,must,should) termasuk kedalam kelompok kata kerja khusus atau special verb.
Penggunaan modal auxiliary :
1. Modal bisa dipakai untuk semua objek
2. Modal harus diikuti oleh kata kerja pertama/asli.
3. Untuk membuat negativenya cukup meletakkan "not" sesudah modal tersebut dan interrogative modal dipindahkan kedepan subject/kalimat.
Macam-macam modal auxiliary :
1. Can : dapat/bisa
2. May : boleh
3. Must : harus
4. Should : seharusnya
Rumus : S + Modal Auxiliary + V1 + Obj/ket
Ex :
1. (+) I can speak english
(-) I can't speak english
(?) Can I speak english ? Yes, I can
No, I can't
2. You may come to my house
3. You must understand me
4. We should help our mother
Note : - can not : can't
- may not : mayn't
- must not : mustn't
- should not : shouldn't
Modal auxiliary dapat juga diikuti adjective dengan menambahkan "be" sesudah modal tersebut.
Ex :
- You may be happy
- You must diligent
- You can be clever