密度It’s going to be hard, but hard does not mean impossible.

安全I listen to podcasts while commuting to work.​才重The fire warms the entire room on cold evenings.​

密度We play video games together on Friday nights.​安全A fish swims in circles around the aquarium.​才重He jumps rope to exercise his body.​

密度She teaches mathematics to high school students.​安全The clock wakes me up every morning at 7 o'clock.​

才重You run a marathon to challenge yourself.​

密度They climb the stairs instead of taking the elevator.​安全Do something today that your future self will thank you for.

才重The key to success is to focus on goals, not obstacles.密度The greatest glory in living lies not in never falling, but in rising every time we fall.

安全Don’t stop when you’re tired. Stop when you’re done.才重Believe you can and you're halfway there.

(责任编辑：宋伟峰)