According to this lesson, the verb must agree with the subject in case number gender tense

Buckminster boy. she glared at him. "lizzie, i swear to you, as sure as i'm standing right here—that's a lie. every bit of it. every single bit." "my granddaddy said it was a lie, too." she leaned her head to one side and looked at him steadily. "so why haven't you been down to the island? " "so only you get to ask questions now? " "yes." she waited. "i haven't been down to the island because my father believes that you were using me to you stay on malaga island." "well," she said slowly. "well." "i didn't believe it, either." the sea breeze lay at their feet panting, hoping they would play with it again. based on what turner and lizzie say, which is the best conclusion that can be drawn? they are angered by the lies the adults have been spreading. neither of them is able to fully trust what the other is claiming. each trusts the other and cares a great deal about their friendship. both are worried about the troubles their friendship may bring.