I assume you mean the three tenses, but let me know if you need more.
Past Tense: "Birds flew in the sky."
Future Tense: "Birds will fly in the sky."
The sentence is already in the present tense.
Answer:
the answer is A
Explanation:
because they wanted to to develop more efficient ways to travel and wanted to expand their power in the world
In lines 140-150, what hasn't changed is that the father still switches off the electricity generator at 10 p.m. and goes to sleep in his study. The expression "as was custom" marks that this has not changed.
The language that shows that the father is changing can be found in lines 141, 173 and 175-176:
In line 141 we learn that he does not use certain rooms ("rooms we'd stopped using").
In line 173 we read that the father "seemed lighter" and chatted with his son.
In lines 175-176 the father says that "now he might be able to come to the end-of-the-year recital" at his child's school.
Please, show me how to ride a bike!
Answer:
improving air quality :
1. keep it clean. a clean house may be a healthier house , because good indoor hygiene can greatly cut down on dust and animal dander
2. keep the greenery outdoors
3. change your filters
4. invest in an air purifier
5. let fresh air in
