1.   A thin squeaking betrayed the presence of two baby gold crests, precariously balanced on the branch of a larch.

2.   He held his breath, not wanting to make the slightest sound that might betray his presence.

3.   He veered to his right, not wanting to betray his presence with dust from the dry mud of the lane.

4.   Or did they simply betray the presence of a lone woman in a dark deserted place?

5.   The floor was covered with large red and white vinyl tiles, rubbed in ridges that betrayed the presence of flagstones underneath.

6.   The slightest sound might betray his presence.

7.   She coughed, betraying her presence behind the door.

8.   Although invisible, their gravity bends light from background stars, betraying their presence.

9.   Black holes have also betrayed their presence by sucking in matter from nearby space.

10.   A slight tremor in these bursts betrays the presence of an invisible captive, a companion star so close that it orbits the X-ray pulsar every two hours.