a. The weather was very beautiful. They spent all day watching birds in nature.
→ The weather was such a beautiful sight that they spent all day watching birds in nature.

b. The hobby is very interesting. Many people enjoy having it.
→ It is such an interesting hobby that many people enjoy having it.

c. The gifts were so expensive that nobody had enough money to buy them.
→ They were such expensive gifts that nobody had enough money to buy them.

d. It was such a difficult test that nobody got good marks.
→ The test was so difficult that nobody got good marks.

e. The hobbies are so interesting that everyone wants to have them.
→ They are such interesting hobbies that everyone wants to have them.