`1.` Getting./plenty/rest/really/important.
`⇒` Getting a plenty of rest is really important.
`2.` It /easy/get/flu/./we/should/try/keep/clean/more/.
`⇒` It is( easy to get flu. we should try to keep clean more.
`3.` He/has/flu/./he/keep/sneezing/coughing/.
`⇒` He has a flu. He keeps sneezing and coughing.
`4.` Which/activity/use/more/calories/walking/or/riding/bicycle/?
`⇒` Which activity uses more calories, walking or riding a bicycle.