Then, once you learn a new verb, like "Mimasu" (See), you'll already know "Mimashita" (Saw), "Mimasen" (Didn't see) and "Mimasho" (Let's see). So, if I give you the verbs "Kimasu" (Kee-mas) "comes", "hanashimasu" (ha-nah-shee-mas) "talks/speaks", and "Nomimasu" (No-mee-mas) "drinks", you'll be able to give the past tense (-shita), negative tense (-sen), and an invitation (-sho). So des' ka?
Watashi wa ikimas'. = I go (am going).
Watashi wa ikimasen. = I don't go (are not going).
Ikimasho ka? = Shall we go?
Hai, ikimasho! = Yes, lets go!
Pururun-san wa kimashita ka? = Miss. Pururun came?
Anata wa hanashimashita. = You were speaking."
Nomimasho. = Lets drink.
Biiru nomimasen. = (I) don't drink beer.
O-cha nomimas'. = (I) drink tea.
Adding "-shita" makes a verb past tense, and adding "-sen" makes it a negative, but what if you want to do both at the same time? Like to say "Did not go". For that, you'll need an extra word. First, use the negative ending for the verb, in this case "Ikimasen" = "doesn't go", then add "Deshita" (deh-shee-tah) to make it past tense. "Deshita" is sort of like "Des'" with the negative "-shita" added to it. It works like "Des'" but shows past tense instead of present tense. So, to say "I didn't go" you'd say "Watashi wa ikimasen deshita" or just "Ikimasen deshita" = "Didn't go"
Pururun-san wa ikimashita ka? = Miss. Pururun went?
Iie, Pururun-san ga ikimasen deshita. = No, Miss. Pururun did not go.
Hai, Sukashii-san ga ikimashita. = Yes, Mr. Sukashii went (did go).
Pururun-san ga doko ikimashita ka? = Where did Miss. Pururun go?
Mimasen deshita = (I) didn't see.
Piza wa tabemashita ka? = Did you eat the pizza?
Mo tabemashita. = Already have eaten.
Mada tabemasen. = Haven't yet eaten.
Study, and don't hesitate to go back over the previous lessons if you can use a refresher.
*Remember, that silent "U" when dealing with Japanese words that end with the "su". "Masu" and "Desu" sound more like "Mas" and "Des".