#### Answer

acute;
right;
obtuse;
straight

#### Work Step by Step

RECALL:
An acute angle has a measurement between (but not including) 0 and 90 degrees.
A right angle has a measurement of 90 degrees.
An obtuse angle has a measurement between (but not including) 90 and 180 degrees.
A straight angle has a measurement of 180 degrees.
Thus, the missing expressions in the given statements are (in order):
acute;
right;
obtuse;
straight