填空题 Put the underlined phrases in an internal email into a less formal style.
Dear Jim
I hope you are well. I {{U}}apologise for{{/U}} (I'm sorry about) the long delay in replying to your email. {{U}} {{U}} 11 {{/U}} {{/U}}{{U}}However{{/U}}, I wanted to research your question thoroughly before {{U}} {{U}} 12 {{/U}} {{/U}}{{U}}providing you with an answer{{/U}}. You {{U}} {{U}} 13 {{/U}} {{/U}}{{U}}enquired whether{{/U}} it was possible to extend the life of our standard mobile phone battery, {{U}} {{U}} 14 {{/U}} {{/U}}{{U}}since{{/U}} you have received a {{U}} {{U}} 15 {{/U}} {{/U}}{{U}}significant number{{/U}} of complaints about it. The answer is 'yes', but the solution may be expensive. We source our batteries from a Korean supplier which manufactures three different grades of battery. The ones {{U}} {{U}} 16 {{/U}} {{/U}}{{U}}which we purchase{{/U}} are the cheapest in the range. {{U}} {{U}} 17 {{/U}} {{/U}}{{U}}It will come as no surprise that{{/U}} they also have the shortest life.
If you {{U}} {{U}} 18 {{/U}} {{/U}}{{U}}wish{{/U}} me to send you more technical details, {{U}} {{U}} 19 {{/U}} {{/U}}{{U}}please do not hesitate to{{/U}} ask me.