Correct Answer : Unless we do not know
The conjunction 'unless' is used to indicate a negative sense. So, remove 'do not' in the first part of the sentence, e.g., unless we know where to go.
Correct Answer : Option (B) : was behind
Explanation : The word 'behind' in the 2nd part of the sentence needs to be replaced with 'beyond', e.g., Although the stress was beyond her capacity yet she didn't complain.
Correct Answer : Option (D) : like dancing.
Explanation : If the subject is everyone or everybody, the verb must be singular. So, the verb in the fourth part of the sentence must be singular, e.g., likes dancing.
Correct Answer : Option (C) : as she
Explanation : In this sentence, the intent is to convey 'from the time' she came, so replace 'as' with since, e.g. She has been studying with me since she came here.
