This plant lives (under the water.)对括号部分提问
(where does this plant ) live?
To read this book is boring for him.(改为同义句）
(It is broing for him ) to read this book.
They must be back by 10:00 p.m at night.(改为一般疑问句）
(Must they be back ) by 10:00 p.m at night?
We can (ask people not to kill animals ) to protect the Earth?对括号部分提问
( What can you do ) to protect the Earth?
People shouldn't put rubbish into the sea.(改为祈使句+
(Don't put rubbish ) into the sea.
加油!不明白再问!