~hō ga ii desu  

“~hō ga ii desu” means “It’s better to do something”. For instance, “Kusuri o nonda hō ga ii desu” means “It’s better to take medicine”. Remember that the verb must be converted to past tense when using this sentences. As shown in the above example, “Nomu” (Drink) is converted to “Nonda” which is past tense. However, when using this sentence for negative phrase, no past tense shall be used. For example : “Kusuri wa nomanai hō ga ii desu” (It’s better not to take medicine). See it doesn’t use “nomanakatta” (past tense) instead “nomanai” (present tense) is used.

As usual, “o” shall be used after the noun for positive phrase and “wa” is used for negative phrase.

Other Examples
It’s better to eat more vegetables – Yasai o takusan (taberu)tabeta hō ga ii desu
It’s better to sleep earlier – (Hayai)Hayaku (neru)neta hō ga ii desu
It’s better not to go too far – Amari (tooi)tooku e wa (iku)ikanai hō ga ii desu
Meaning : Yasai (Vegetables), Takusan (Many / More), Neru (Sleep), Hayai (Fast), Tooi (Far), Amari (Not So)

~nakereba narimasen & ~nakute mo ii desu  

~nakereba narimasen – It’s not right not to do something (have to do)
~nakute mo ii desu – It’s fine not to do something (do not have to do)

To use these, you have to change the the verbs to negative (ie. (tomeru)tomenai, kaku(kakanai), miru(minai))

You have to stop the car – Kuruma o tomenakereba narimasen
You don’t have to stop the car – Kuruma o tomenakute mo ii desu

Other Example
Q : Bōshi o (kaburu)kaburanakereba narimasen ka?
A : Hai, bōshi o kaburanakereba narimasen (Positive Answer)
A : Iie, bōshi o kaburanakute mo ii desu (Negative Answer)
Meaning : Bōshi (Cap), Kaburu (Wear/Put On)

Q : Kimono o (kiru)kinakute mo ii desu ka?
A : Hai, Kimono o kinakute mo ii desu (Positive Answer)
A : Iie, Kimono o kinakereba narimasen (Negative Answer)
Meaning : Kimono (Japanese Tradisional Wear), Kiru (Wear)

mo ii desu & wa ikemasen  

“mo ii desu” (can do something) and “wa ikemasen” (cannot or not allow to do something). You have to use ~te form for the verbs just before the above sentences. Rules : Verbs (~te form) + “mo ii desu” or “wa ikemasen”

Q : Can I smoke cigarrette? – Tabako o (suu)sutte mo ii desu ka?
A : Yes, you can smoke cigarette – Hai, Tabako o sutte mo ii desu (Positive)
A : No, you cannot smoke cigarette – Iie, Tabako o sutte wa ikemasen
Meaning : Tabako (Cigarrette), Suu (Smoke)

You can stop your car – Kuruma o (tomeru)tomete mo ii desu
Can I go back now – Ima, (kaeru)kaete mo ii desu ka

Form a sentence in English and try to use the above sentences.

Conversation  

Conversation 1
Q : Already received your birthday present? – Mō tanjōbi no purezento o moraimashita ka?
A : Yes. I got a cassette tape from Tony – Hai. Toni san ni wa kasettote-pu to sara no setto o moraimashita.

Q : Any other? – Hoka ni wa?
A : I got flowers from the teacher – Sensei ga, hana o kudasaimashita.
Meaning : Mō (Already), Tanjōbi (Birthday), Purezento (Present / Gift), Kasettote-pu (Cassette Tape), Hana (Flower)

Conversation 2
Q : Still haven’t water the flowers – Mada hana ni mizu o (yaru)yatteinai no
A : No, already done this morning – Uun, kesa wa mō yatta yo
Meaning : Mada (Still), Mizu (Water), Yaru (Do), Kesa (This Morning)

Conversation 3
Q : Very soon will be dad and mom’s wedding aniversary. Last year what dad gave to mom? – Mō sugu otōsan to okaasan no kekkon kinenbi ne. Otōsan wa kyonen, okaasan ni nani o ageta no?
A : A diamond ring – Daiyamondo no yubiwa da yo
Q : Wow, amazing – Waa-, sugoi.
Meaning : Sugu (Soon), Kekkon (Marriage / Wedding), Kinenbi (Aniversary), Kyonen (Last Year),Daiyomondo (Diamond), Yubiwa (Ring), Sugoi (Amazing / Wonderful)

Conversation 4
Q : What are you going to give to dad during christmas – Otōsan ni kurisumasu no purezento, nani ageru?
A : Oh ya. How about a tie? – Sō da na. Nekutai wa dō?

Q : That was given a year before last year – Sore wa ototoshi ageta wa
A : So, how about a wallet – Jaa, saifu wa?
Q : Hmm, let’s go for wallet. I will go and buy tomorrow – Sō ne, saifu ni shimashō. Watashi ga ashita katte kuru wa
Meaning : Kurisumasu (Christmas), Nekutai (Neck Tie), Ototoshi (A year before last year), Saifu (Wallet)