EmpResWrit-Wk3: Verb Tense Race!

Air quality in cities (3) ________(be) currently significantly lower than in rural areas...

...and this (4) ___________ (show) to be directly linked to the level of vehicle emissions from private cars (see, for example, Rivera, 1985; Maslin 1990; or Sharpe, 1994).

Due to the fact that urban transport policy in the UK is designed to reduce or discourage the use of private cars, there (5) _______________ (be) an increase in the sale of non-polluting vehicles such as the SPPPV (Single-Person Pedal-Powered Vehicle).

However, although the number of SPPPV users (6) __________ (increase), safety and comfort issues need to be addressed if the number of users is to increase to a level at which a significant effect on environmental pollution can be achieved.

Researchers (7)  ___________ (study) and improved many aspects of the SPPPV.

In 1980, Wang et al. (8) ___________ (respond) to the need for increased safety by designing an SPPPV surrounded by a ‘cage’ of safety bars, ...

... and in 2001 Martinez (9) ___________ (develop) this further with the introduction of a reinforced polymer screen, which could be fitted to the safety bars to protect the cyclist’s face in the event of a collision.

The issue of comfort has also been addressed by many design teams;  in 1998 Kohl et al. (10) _________ (introduce) an SPPPV with a built-in umbrella, which could be opened at the touch of a button, ...

... and more recently, Martinez (11) __________ (add) a mesh filter, ...

... which can (12) ________  (place) over the entire cage to reduce the risk of environmental pollution.