The magician picked ________ several from the audience and asked them to help him with the performance.
句意： 魔术师从观众席中随机挑选了几位观众， 并请他们帮他表演。 at random随机地， 任意地。 by accident偶然， 意外地。 on occasion有时， 偶尔。 on average一般说来， 通常。