Nobody taught the old lady how to use Wechat． She learned it all by ____．（ ）
A．sheB．herC．herselfD．hers
Students in our school ________ know shouting is not allowed in the library．（ ）
A．canB．mayC．mustD．need
The little boy his seat to an old lady on the crowded bus．（ ）
A．lentB．offeredC．tookD．brought
You'd better make a good plan________ you take a holiday．（ ）
A．beforeB．duringC．untilD．after
A smile costs ， but gives so much．（ ）
A．somethingB．anythingC．nothingD．everything
Lisa was so careless that she made many spelling ________ in her homework．（ ）
A．plansB．decisionsC．gradesD．mistakes