Jawaban:

1. Don't smoke here. the signs indicate it

alasan : karena must artinya 'harus' sdgkn pd

kalimat ada kata 'signs' yg berarti

'tanda'

2. You shouldn't go in public if it's not necessary

alasan : not necessary artinya 'tdk perlu', berarti

kata yg tepat shouldn't

3. You must wear a mask if you go outside

alasan : karena kalimatnya merupakan kalimat perintah maka kata yg tepat 'must'

4. She shouldn't ear candies. It is not good for your health

alasan : kalau should itu lbh ke menyarankan. Sdngkn must lebih ke melarang/memerintah. Jadi yg lebih tepat 'shouldn't'

5. You mustn't take photos here. It is not allowed

alasan : bedanya don't dgn mustn't yakni mustn't itu larangan sdgkn don't tdk adanya keharusan