[While Martha catches the words, she's not versed enough in Latin to understand them. It occurs to her that Helen is not the Doctor, and doesn't feel the need to fill the vacuum of silence with the sound of her own voice. Martha's good at staying quiet though. When Helen does speak next and doesn't say anything, Martha fixes her with a look.]
Helen...
[That's all she says. It's more quiet than insistent, but clearly says Martha expects more than just beating around the bush.]