a. Complete the text
2. bigger (so sánh hơn giữa flower và the rafflesia
3. heavier (cũng là so sánh hơn; vì heavy là tính từ ngắn nên adj(short) + er, còn tính từ dài như beautiful thì more + adj(long); câu này so sánh the rafflesia với a one- year-old child.
4. bigger (so sánh the rafflesia với a large bicycle wheel)
b. Write about the smallest bird in the world

The Bee Hummingbird is the smallest bird in the world and it's so cute. Firstly, It's just bigger than a bee a little bit but smaller than a large spider. Secondly, The Bee Hummingbird is so colorful because its skin color includes blue, red, and absolutely green. Moreover, between the male bird and the female bird, there is a little difference in size that the female will be bigger than the male. Finally, the male never sits on the eggs, but the female will do it instead. 

CHÚC BẠN HỌC TỐT NHÉ^^