Double Bubble Game

In this game there will be a number of objects appearing from the bottom of the screen. When an object first appears, do not click it, after it has appeared a second time, click it. When the game progresses there will be more objects to click and there will be more different objects. If you cannot find the specified number of objects within a certain time limit, you lose the game. If you clicked a wrong object, scores will be deducted and the number of remaining seconds will also be deducted.

Can you remember which object has appeared before?