What are the keywords in the following sentence? a small herd of sheep eat some grass under the trees
grass, herd, sheep

What are the keywords in the following sentence? kindergarten and elementary school students around country participate in various activities to promote a greener world .
country, promote, world

What are the keywords in the following sentence? hoar frost covering the market town in winter
cover, frost, hoar, winter

What are the keywords in the following sentence? yellow and maroon orchid hybrid flowers grow in a botanical garden
flower, garden, orchid