________ Simon has done well in his studies, he still works really hard.
句意：虽然Simon学习很好，但是他仍然努力学习。
考查连词辨析。Since既然、自从……以来，引导原因状语从句和时间状语从句；If如果，引导条件状语从句；Although虽然，引导让步状语从句；Unless 除非，引导条件状语从句。根据Simon has done well in his studies,以及 he still works really hard.可知前后句之间存在一种相反的让步关系，所以用Although引导让步状语从句，故答案选C。
________ Simon has done well in his studies, he still works really hard.
We will cause less pollution _________we can find ways to reuse or recycle more rubbish.
Many students hated to have classes on DingTalk, ________ they gave it one-star reviews（评价）.
______ he is dead, Kobe Bryant’s spirit will continue to influence us.
______ the traffic was heavy, we still got to the railway station on time.
I’ve tasted lots of delicious food, ______ what I like best is the dishes _______ by Mum.
—My parents are crazy about Running Man. How about your parents?
—______my dad_______ my mom likes it. They are interested in The Voice of China.
—Did you catch the first bus to school this morning?
—No I didn’t. It had started moving ______I could get on it.
Life is like a horse, and ________ you ride it ________it rides you.
—Labor(劳动)education is important for students' development.
—Yes. ________schools put it into practice, students will be more independent and helpful.
