13. It's easy to keep cacti.
仙人掌很好養活。
還能這樣說：
Cacti can be easily kept.
It's not difficult to keep cacti alive.
應用解析：
in bad keep 保存得不好；
in good keep 保存得好；
keep from 避開；禁止；隱瞞；
keep on with 繼續
14. Can you give me some advice about how to plant camellia?
關于養茶花你能提些建議嗎？
還能這樣說：
Could you tell me how to grow camellia well?
Can you teach the methods of growing camellia?
諺語：
Many receive advice only the wise profit by it.
得到忠告的人很多，唯智者能從中受益。
15. We have a grassy lawn in our garden.
我們的花園里有綠草如茵的草坪。
還能這樣說：
You can see a green turf in our garden.
Our garden is covered with grassy lawn.
諺語：
The neighbor's lawn is green.
鄰家的草坪綠（老婆別人的好）。
16. Keep off the grass, please!
請勿踐踏草坪！
還能這樣說：
You're not supposed to walk on the grass.
You are not allowed to walk on the lawn.
應用解析：
cut one's own grass 自食其力；
cut the grass from under sb.'s feet 妨礙某人；拆某人的臺；
hear the grass grow 特別敏銳
17. The flowers have withered away.
花謝了。
還能這樣說：
The flowers have fallen and scattered about.
The flowers have sicken.
應用解析：
the flower of the youth of the country 國家的優秀青年；
no flowers (by request) 花圈敬辭；
as welcome as flowers in May 極受歡迎的