B
backpack ——> knapsack
be crowded —— > be well-attended
be done —— > complete
be free —— > not busy
be in one ear and out the other —— > doesn't listen
be onto something —— > promising
be overwhelmed with —— > be busy with
beach —— > seashore
best score —— > perfect grade
beyond sb. —— > not understand
big sale —— > discount