Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

An exterior architect is asked by a builder to plant seven trees in a manner that there are exactly six rows of trees in a straight line and each row has three trees in particular.

How will he do it?

What word begins and ends with an E, but has only one letter?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

1. How can we put an elephant in the refrigerator?
2. How can we put a Giraffe in a refrigerator?
3. The king of the jungle invites all the animals to a party everyone comes except for one animal, which animal?
4. You come to a crocodile-infested lake, you can't go around it, you can't co under it and you can't go over it, how do you get across?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

How many words can a pen with half refill write?

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

The doctor prescribed you to take one pill from the bottle every half an hour. The bottle is now left with only three pills.

How long do you think you have before you run out of pills?