State one design feature the technician could use in order to ensure a very sensitivethermometer.

One design feature that a technician could use to ensure a very sensitive thermometer is to use a smaller bulb and a narrower bore. This design would allow for a larger change in the volume of the liquid (usually mercury or alcohol) for a small change in temperature, thus increasing the sensitivity of the thermometer.

Step by step:

1. Choose a smaller bulb for the thermometer: A smaller bulb will contain less liquid, which means that a small change in temperature will cause a relatively large change in the volume of the liquid.

2. Use a narrower bore: A narrower bore will mean that a small change in the volume of the liquid will result in a larger change in the height of the liquid column, making the thermometer more sensitive.

3. Combine these two features: By combining a smaller bulb with a narrower bore, the technician can create a thermometer that is very sensitive to changes in temperature.