Rectangular matrices question

hi,

I have a question on determining whether rectangular matrices are singular.

$$\left[1 0 0 1 0\right]$$
$$\left[1 0 0 0 1\right]$$
$$\left[0 1 0 1 0\right]$$
$$\left[0 1 0 0 1\right]$$
$$\left[0 0 1 1 0\right]$$
$$\left[0 0 1 0 1\right]$$

The book says it's singular. But the explanation isn't very clear. It says something about the first 3 columns treated as vectors give a column of 1's, the final two columns also give a column of 1's. Any better explanation?