Have you to Singapore? * 4 points
be
been
being
went

Have you been to Singapore?

Explanation:

Have you be to Singapore, have you being to Singapore, have you went to Singapore are all the wrong tenses.

Have you been to Singapore is in the right time tense.

onto a large boat, and mark the water level that the boat sinks to. then, take the elephant out and put a bunch of marked weights onto the boat until it reaches the same water level. add up the masses of the weights to get the weight of the elephant.