If she cries for long periods of time for seemingly no apparent reason, it can be very stressful. (littleremedies.com)
You can set the length of each study session; you could complete the course in one day or study for short periods of time over several days. (nationalhighwaysafetyadministration.com)
You can work tirelessly for extended periods of time on long - term projects without feeling like you're missing out on something. (entrepreneur.com)