telltale

In July, El Sobrante staff told the local air district the landfill had experienced a rise in highly flammable hydrogen gas and lung-aggravating dimethyl sulfide emissions — both telltale signs of abnormal temperatures inside the landfill.

Hubble worked hard, taking images of spiral nebulae every clear night and looking for the telltale variations of Cepheid variables.

Beneath the surface of this country’s seeming strength, we could already see the telltale signs of decline that had led to the collapse of those earlier empires.

And it worked with Energizer on safety features including a telltale dye that turns blue with saliva.

Carefully check the URL of a website to ensure that it’s legitimate — even minor variations in spelling or style are a telltale sign of a scam.