Here are the answers in Chinese characters and pinyin:

1. This is dad's dog. / Dyma ci dad. 

这是爸爸的狗。 (Zhè shì bàba de gǒu.)

2. That is younger sister's fish. / Dyna pysgodyn chwaer fach. 

那是妹妹的鱼。 (Nà shì mèimei de yú.)

3. This is mum's bird. / Dyma aderyn mam. 

这是妈妈的鸟。 (Zhè shì māmā de niǎo.)

4. That is elder brother's cat. / Dyna cath brawd mawr.

那是哥哥的猫。 (Nà shì gēge de māo.)

Now, it's time to practice your pronunciation. Listen to the provided audio and repeat each sentence after it to improve your spoken Mandarin skills.