Identify the tense combinations of these sentences

Durable goods reflect a purchaser's high level of involvement in the purchase decision.

(a)  

These tools are constructed according to the beliefs and values of the elite.

(a)  

The majority, perhaps 75 per cent, are moving by saltation.

(a)  

It might seem artificially to constrain the choices that are being voted upon.

(a)  

The internet and the world wide web have provided a new medium for culture.

(a)  

It has been argued that certain institutions should be disbanded.

(a)  

Teacher Jp has been working here for 6 years.

(a)  

These theories led to the concept of how to measure intelligence.

(a)  

Some of the most influential research on culture and the workplace was carried out by Hofstede.

(a)  

Even though Australia was running a large trade surplus in agricultural products with South Korea there their diplomatic relationship remains strong.

(a)