They know. (saber)

(a)  

They go. (ir)

(a)  

They investigate. (investigar)

(a)  

They make.

They do. (hacer)

(a)  

They travel. (viajar)

(a)  

They are. (ser)

(a)  

They leave. (salir)

(a)  

They sleep. (dormir)

(a)  

They see. (ver)

(a)