which is correct?

[Unregistered]

Dear teachers.

1. Which is correct?
(1). Look what I bought.
(2). Look at what I bought.

2. Which is correct?
(3). You look like you've lost some weight.
(4). It looks like you've lost some weight.

[Casiopea]

Dear teachers.

1. Which is correct?
(1). Look what I bought.
(2). Look at what I bought.

2. Which is correct?
(3). You look like you've lost some weight.
(4). It looks like you've lost some weight.

They're all correct. Though, in terms of traditional grammatically (3) and (4) should be "looks as if".