根据所给提示，完成下列句子。每空一词，含缩略词。
You need to look up the word in the dictionary. (变否定句句)
You ________ ________ to look up the word in the dictionary
I’d like to go to Guilin on vacation.（对划线部分提问）
Where _________ you _________ to go on your vacation? 
Linda takes care of her younger sister. (同义句)
Linda ________ _________ her younger sister.
当他正走在街上时，看见事故发生了。
He saw the accident _________ while he was _________ down the street.