هل يمكنه استئناف التنزيلات المقطوعة؟

Yes. GDM writes its progress as it goes, so after a lost connection, a crash or a restart it carries on where it stopped. Before resuming it checks that the file on the server hasn't changed. When a download address has expired, Refresh download address lets you give it a fresh one and keep the data. See Resume a broken download.